WMG / Back to the Future Part II

January 1st, 1885 is the Deloreans Unix Epoch.

It's not like Doc had that date on speed dial or anything. The plan was to burn the book, Get Back to the Future, and destroy the time machine. There was no detour to the wild west in that schedule. Not only do the Time Circuits reset to this date before he gets struck by lightning, but also before making the trip back to 1955 (until Doc performs some Percussive Maintenance on it, which switches it back to the input time). It would make perfect sense if JAN / 1 / 1885 is 00:00:00. Depending on Docs programming, it might even be the furthest point backwards they could actually go.

The 2015 of Back to the Future Part II was erased.

Think about it! History was changed three times, once by Biff, a second time by Marty traveling back to 1955 to stop Biff, and again in 1885 by Marty and Doc in Back to the Future 3. The new 2015 that resulted is basically our timeline as it exists now. In 2015, a Back to the Future 4 will be released in which Marty Jr accidentally goes back to 1985.

• The last part is jossed. No fourth film was released. At best, LEGO Dimensions joked about BTTF's version of 2015.

The 2015 of Back to the Future Part II was erased by paradox.

A lot of them!

• Jennifer saw herself, Biff returned to a 2015 that by the new timeline he created in 1955 was impossible, and thus Biff got erased.
• Marty and Doc then traveled back in time using a time machine that should no longer exist in the timeline they exist in now, however old Biff's desire to return to 2015 results in a possible timeline where he does, simply by punching in "last time departed".
• In this possible timeline, Marty and Doc enter the time machine with the desire that they go to their 1985. However, Doc fails to notice that the time machine's "last date traveled" is set to 1955. The time machine's computer then calculates 1985 from the 1955 it created. This erased both Marty and Doc's 1985, but not, from the time machine's perspective, Marty and Doc. This also erases the 2015 they just left. By traveling back to 1955 from the alternate 1985, they rewrite history again, creating yet another alternate 1985, and another alternate 2015.
• The timeline was able to create a stable time loop where, because Doc died soon after coming to town, history was not sufficiently altered to erase Marty. Because of Doc's earlier paradox encountering his older self, forming a quantum entanglement if you will, it was drawn back to Marty in a self correcting loop. Since Marty failed to die, this self correcting time loop was erased, creating an alternate 1955, 1985, and 2015.
• The alternate 1985 of Eastwood Ravine was one of self-correcting paradoxes. Since Marty was successful, the stable time loop of 1955 was allowed to continue along a similar enough path that they still buried the time machine in 1885 for Marty to dig up in 1955, allowing Marty to go back to 1885. But again, 1985 is the 1985 that the time machine would calculate which is the most correct, however, the only evidence for the 2015 it's previously been to was destroyed, and thus it can't calculate its causality; all this leaves that 2015 open, as long as Marty doesn't use his knowledge of the future to change history. But Marty did, and didn't race Needles, and thus the 2015 of "Your Fired" is erased, but the paper isn't because the paper of 2015 was recycled from paper of 1985. A new 2015 is created because Marty and Jennifer reject the 2015 they left. Since the 2015 they left was still unstable from the triple paradox of Jennifer seeing herself, Old Biff using "last time departed", and Marty and Doc using the time machine to return to 1985, it was hit by waves of instability coming from a massively unstable 130 year long timeline with multiple self-correcting time loops. The final paradox, the straw that broke the universe's back, was Marty and Jennifer using their knowledge to prevent it from happening.
• Meanwhile at an earlier point in the same timeline, over many years, Doc buys a steam engine, uses his knowledge of nuclear physics to very carefully create plutonium in the 19th century, and hops into the time machine with his wife and kids. Since this took place before Marty and Jennifer decide to use future knowledge to prevent future events, thus splitting the Eastwood Ravine timeline, the steam engine would go to one of two 1985s, one where Marty and Jennifer get into the accident, and one where they don't. Since this is the one where they don't, that 2015 is rejected and thus erased, and this current 2010s is the one we'll get, not the exponentially more impossible 2015.
• The only X factor is, where will Doc go in his time train? Do we exist in the "Eastwood Ravine" timeline? Is that timeline erased by Doc's next destination? And if so, are we the timeline of that 2015, or one of the many 2015s that were erased?
• The highest statistical likelihood, stemming from the majority of time travel experiences described in the English language, is that we are now in the timeline created by the Doctor when he showed up behind the scenes to save both the universe and the Milky Way galaxy (or Mutter's Spiral, if one prefers) from being destroyed by all these temporal causality paradoxes. As such, if the ravine is found, there is a strong possibility that it now reads "Smith Ravine".

In 1955, Biff doesn't live with his grandmother.

He lives with his step-mother, Edna. He just calls her "grandma" as an insult.

• This is in violation of the first rule of BTTF time travel: you can never see the effects of your own time travels before actually performing those time travels.
  • The whole premise of Back To The Future Part II is a violation of this rule, because Marty and Jennifer see their children despite, from an external perspective, having just disappeared for 30 years. They should not be able to see their children because they haven't travelled back in time to 1985 yet, nor got old enough to finish school, get married and have those kids in the first place.
    • No No NO! That only applies if they had opted to stay in the future.
    • This is because the ripple effect takes subjective time on the time traveler's part to take effect. One can travel into the future and meet his future self, but if he stays long enough, his future self will fade away... that is, until the time traveler returns to the past.
• Jossed. According to the sign on Biff's grandmother's house, her name is Gertrude Tannen.

The DeLorean door opening killed Biff.

In a deleted scene, we see old Biff dissappear after changing the timeline. that's because in A 1985, The door opening killed A Biff, so Old biff didn't exist.

• Jossed by Word of God: DVD special features for Part II state that Biff was killed in 1996-A, most likely by Lorraine, who was sick and tired of the abusive marriage and may have found out what happened to George.

Doc's inventions created the futuristic 2015 of the movie.

The reason why the 2015 in the movie looks nothing like what the true year of 2015 will be is because we're in a reality with no Doc Brown. The man is a genius who is WAY ahead of his time and it's fairly likely that he'd be capable of many other inventions after mastering time travel. It's possible then that everything from hoverboards to hovercars and anything else you saw in that futuristic 2015 were all based on Doc Brown's prototypes. Still odd how cell phones or laptops don't exist in that reality though.

• Cell phones and laptops may very well be children's toys in that reality.
• In an alternate flow of technological development ushered in by Doc Brown the resources that would have gone into the things in the Prime timeline (ours, without Doc) that we take for granted were never invented. The financial resources that would have gone into developing cell phones instead went into developing hoverboards, etc. So while that universe seems to have technological advancements that would take our breath away, we also have technological advancements they would find amazing. There's always a karmic balance to messing with timelines.
• More radically : the laws of physics work differently in the BTTF universe. Remember they have Time Travel in 1985. Doc may be a genius, but that means Time Travel was easier to understand in their universe than in our own, where there isn't even any theory of how it should work, if it is possible at all.
• Even more so when you consider and include the events of the Back To The Future: The Ride, where he founded the Institute of Future Technology, dedicated to creating tech that could shape the future. So, without Doc Brown, no Institute. No Institute, no 2015. Doc could have looked up what happened to him in the years between 1985 and 2015, discovering his achievements. Also, it would account for why he allowed Marty to bring the Hoverboard with him while chastising him for trying to take the Sports Almanac for financial gain, so he can reverse engineer it and start the ball rolling on hover tech and sending the world onto the path of the 2015 seen.

Old Biff's reason for choosing November 12, 1955:

When Old Biff gave the Timeline-Altering MacGuffin to his younger self on the date of the lightning storm, it was no coincidence. Biff chose that date because he believed that that day was the day that his entire life changed. And it was. Getting decked by George turned him from a bully into a relatively nice guy a wimp afraid of his former victim. Old Biff decided that that life sucked, and he still had a grudge against George McFly, and so he went back to the moment that things changed.

• There's a deleted scene from Part II where the Clock Tower Guy in 2015, Terry, reminds Old Biff of the date while shaking Marty down for money. Terry was the mechanic who told Biff it was 300 bucks for getting all that manure out of his car. Probably hearing about the manure helped remind Old Biff of all the other stuff, so yeah. Off to November 12th!
• That's the only date where Old Biff can remember exactly where he would have been in the past, so he knew he would be able to find himself.

Marty's daughter is transgender

Yeah, Michael J. Fox played the part, but seriously, what woman has gams like that? It's never brought up on-screen because, well, it's the future, and such things are no longer an issue.

• Marty's kids are identical twins with one of them being transgender. The reason Marty is accepting of his kid being transgender is partially due to Doc blurting out to 1985 Marty about having a daughter.
• Possibly implied by Craig Shaw Gardner's novelization of Part II:
  The teenager shrugged her broad shoulders. She was built sort of huskily for a girl, Jennifer thought, probably one of those high school athletic types.

The father of the family that lives in Marty's house in 1985-A is Samuel L. Jackson.

He looks (and sort of sounds) like he's played by Samuel L. Jackson, but he was played by Al White. Instead, the character (only listed as "Dad") is Samuel L. Jackson.

One of the effects of 1985-A is that Samuel L. Jackson's movie career was unsuccessful, probably due to Biff's influence over Hollywood. We know that Biff lobbied in the state capitol and was helping Richard Nixon get elected to a fifth term in office; it's reasonable that he also had some sway in Hollywood. Thus, Samuel L. Jackson settled into a quiet suburban life in Hill Valley.

• I always thought it was Goldie Wilson, who never got to be mayor due to Biff's influence.
  • That would actually make some dramatic sense.
  • If he was intended to be Goldie Wilson, they probably would have gotten the actor from the first film to play him, since he was already in the film as Goldie Wilson III.

1985-A is the same 1985 that Watchmen takes place during.

There is a lot of crime, and Nixon is president. And it would be cool.

• You think a being like Dr. Manhattan wouldn't have something to say about a figure like Biff using an object clearly not meant to be present in this stage in time?
  • It may have something to do with Doc M being created some four years after Biff changed the future.
• But, the headline in 1985-A shows that the Vietnam War was still going on until at least 1983. Whereas in Watchmen, the war was resolved with a quick victory for America.
  • Could be a different Vietnam War. In Watchmen, the US and Russia are implied to have extremely aggressive militaries.
• Doc's family did change their name some time in the past, but in one timeline it became Brown, in another it was Osterman. The split occurred when Manhattan went back and caused his family to settle in California instead of New York, in hopes of preventing his father from becoming a watchmaker.

Marty jumped to his death during 1985-A

When Biff traps Marty on the roof, Doc seems to be waiting for him rather conveniently. It seems likely that Marty died in one timeline, and then Doc heard about it and went back to save him.

• No, because Marty was expecting Doc to be waiting at the roof edge in the DeLorean in the first place — when he hits the edge in anger after looking down it's not because of the height or lack of fire escape but because Doc isn't there. It's set up in the scene where Marty confronts Biff in the jacuzzi, when Biff asks "How did you get past my security downstairs?": Marty bypassed them completely by being dropped off on the roof by Doc. So it wasn't "convenient" that Doc was there — Marty just had to wait for Doc to fly back before he could escape.
• Or maybe it was Marty's plan all along.

Those weren't laserdiscs discarded in the alley in 2015; those were DVDs.

Technology would be marching on and some new technology would be replacing them by 2015. I say "would be" because of the WMG below...

Before his first trip to 2015, Doc had an undiagnosed cancer.

He says he got his colon and spleen replaced and his blood changed, and that treatment added 30 to 40 years to his life. Now, why would that treatment extend his life so much? The answer is: Doc used to have a colon tumor (more common in old people) that metastatized to his spleen, so the future doctors had to replace those organs to remove the tumoral masses. And they changed his blood to flush out the remaining tumoral cells that circulated through his body.

The 47-year-old Marty was one of the "tranqs" the two cops were talking about.

Assuming "tranqs" are people who are addicted to tranquillizers.Evidence: he activates "lithium mode" on a panel, and lithium being used as a tranquillizer is Truth in Television. The lithium mode he activated was probably lithium being added to their drinking water, which is what psychiatrist Peter Kramer proposed in reality in 2009 to reduce suicide rates.

• And 47-year-old Marty is pretty depressed.
• In a deleted scene, Old Marty discovers Old Jennifer passed out (after encountering her younger self). He mutters "She's tranqed again...". So at least one member of the household is tranqing.
• Another possibility is that "Lithium" reffers to batteries. The Lithium Ion batteries we use to day wheren't around in The '80s, but where known to be theoretically possible, hence a "Sci-Fi" technology at the time. "Lithium mode" means that he has the house running on batteries rather than the grid to save money. Obviously the "damned kids" would switch to grid mode so they could have more power to use their electronics. Basically a "Sci-Fi" twist on the classic "damn kids running up the power bill!" problem many fathers have to deal with.

The timeline would've corrected itself

Biff comes back out of the time machine in 2015 and disappears, but the neighborhood doesn't. Hilldale, for instance, was built in 1985 as a nice neighborhood. In 1985-A, it wouldn't have been built altogether. Furthermore, if Doc was committed, he would never have built the time machine, and never allowed Biff the opportunity. Marty and Doc were destined to succeed at saving the future.

• If Doc was committed, he would never have built the time machine, and never allowed Biff the opportunity. So he would have never changed the timeline and Doc would have succeeded in building the time machine and allowed Biff to travel to the past, causing Doc to be committed... and so on. This is what the movies call a paradox.
  • That, however, is based on the unspoken assumption that the events would play out exactly the same way in every iteration of the timeline. There's no reason to assume that that would be the case. It could be that the "paradox" would simply be a recursive correcting agent, replaying the events over and over, slightly different each time, until a consistent timeline unfolded.
  • What does Biff have to do with Hillsdale's existence? There is never any indication that Biff is involved with Hillsdale's creation, the neighborhood itself developed independently from any of the happenings going on in the films (certain nuances would change, but as a whole, it would remain the same). If he disappeared but the neighborhood didn't, that's because he had nothing to do with it anyway. As for the second problem, where by having Doc committed and thus never creating the time machine and thus never acquiring a means to go back in time, I believe that was the idea. Remember that by going back in time and giving his younger self the Almanac, Biff created a new timeline where he is immensely rich and powerful, invalidating the original timeline and thus no longer necessitating the need for the time machine. Marty and Doc should have faded as well since they come from that timeline, but they still existed in spite of that change because the Delayed Ripple Effect of the new timeline had yet to reach them in the future when they traveled to the altered 1985 (the time machine protects them and their memories of any events that occur because of their time-trips).

Griff's gang in 2015 is made up of the grandkids of Biff's 1955 gang

Spike (the girl in Griff's gang) even has a slight physical resemblance to Biff's lackey Skinhead ("get a load of this guy's life preserver").

• So whose grandkid is Whitey (the Asian guy who says "Unless you've got powah!")?
  • Any of them. Biff's gang (and Biff himself) would have been exactly the right age to serve in The Vietnam War, so it's certainly possible one of them came back with a Vietnamese wife, and if his kid married an Asian-American he could have easily ended up with an Asian looking grandson.
    • Biff was born in March 1937 (just subtract 21 years from the 'Hill Valley Man Wins Big at Races' headline date to calculate this). Therefore, he most likely would have been too old to fight in Vietnam and too young for WWII, but he could have fought in the Korean War.
    • Too old to be in the thick of Vietnam, yes, but the right age to be a ranking officer, yes.
    • But the Korean War went from 1950 to the armistice in 1953, so he'd still be too young.
    • US troops have been stationed in Korea since then. He could've easily served a tour of duty there during peacetime.
    • Or one of them (or one of their children) hooked up with any of the many women of East Asian descent already in the US without fighting a war.
    • Whitey's full name according to the newspaper is Chester Nogura, implying Japanese descent on his father's side. So presumably, his mother would be the daughter of one of Biff's gang members under this theory.
• On that matter, Needles' 1985 gang in Part III are probably made up of the descendants of the Tannen gang members throughout the trilogy. Needles' gang members were played by a member of each Tannen gang: J.J. Cohen, who was Skinhead in Biff's 1955 and 1985-A gang in Part I and II, could be Skinhead's son. Ricky Dean Logan, who was Data in Griff's 2015 gang in Part II, could be Data's father. And Christopher Wynne, who was Stubble in Buford's 1885 gang earlier in Part III, could be his great-great-grandson.

Biff didn't have anything to do with Doc's institutionalization in the "Hell Valley" timeline

Even though Old Biff warns Young Biff about "a kid or crazy, wide-eyed scientist" when he gives him the Timeline-Altering MacGuffin, Doc actually went insane because of his inability to understand why the timeline was deviating so much from what Marty told him. Doc would be the only one in the know about how certain future events are meant to unfold.

• Wow...that adds alot of Fridge Horror to the Hell Valley timeline. Suddenly Doc's face in the paper says: I've lost every shred of faith. Please. Please, let me die.
  • Oh it gets even worse: according to the IDW comic, it turns out that 1985A Doc was lobotomized. That's a mental image that'll scar you for life...

Griff is the illegitimate son of Biff's daughter Tiff, who is mentioned in the Telltale game.

This would explain Griff's surname.

• Or Tiff kept her original surname when she got married. That does happen.
  • Technically nobody ever mentions Griff's surname. Doc just calls him "a guy named Griff" and the end credits don't give his last name. The newspaper prop does identify him as Griff Tannen though.

2015 is a dystopia.

• Marty's son is sentenced to fifteen years prison two hours after he's arrested. Why? The justice system moves faster because all the lawyers have been eliminated.
  • And that is evidence of dystopia why...?
    • Lawyers serve a very important role in the legal system. Removing them is pretty much asking for trouble. It was probably a throwaway gag, but it certainly doesn't help given the Cyberpunk/The Future Is Noir feel the rest of 2015 has.
    • As a certain videogame has shown us, the presence of lawyers ensures fair and impartial trials. Remove them and good luck trying to prove yourself innocent against a potentially biased court.

Biff didn't kill off Doc in 1985-B because he, to an extent, realised the Almanac's origin.

At first, all Biff knew about the almanac was that "some relative" knew a guy who could see into the future. With millions of dollars and the years passing, Biff eventually became more intelligent and started to realise how his Gray Sports Almanac could tell the future-then he met the wild-eyed professor Doc Emerett Brown. After interrogating him, Biff put two and two together and figured out that a time machine brought back the Gray Sports Almanac, and that Doc Brown will one day build it. Wanting Doc Brown to not be a threat yet needing his genius, he had Doc Brown committed and looked after in a makeshift duplicate of his lab. His cronies gave Doc the technology to design the DeLorean, and had this timeline progressed Biff would've used it to go back and give himself the Gray Sports Almanac. Anything he's saying to Marty-A is partly him playing dumb.

Her Majesty the Queen meets with an unfortunate car accident, not Princess Diana, in part II's 2015 timeline

After all, by 2015, Queen Elizabeth II would only be 89 by 2015, which given her mother's great age at her death, would mean she'd almost certainly be very much alive if she were eventually to die of natural causes. Only an accident would put Charles on the throne, and hence Diana as queen, so soon. (Of course how she survives her marriage to Charles is another matter- maybe he gives up on Camilla pretty quickly for the sake of fulfilling royal duty? Who knows...)

The universe wouldn't be destroyed if Jennifer met herself.

It's just the Doc being paranoid, which has been seen to happen occasionally (like where he insists on not knowing anything about his own future, even when it will save his life, and later relenting. After all, this effect's possibility is only assumed because we might be inclined to take the Doc's word for it.

Or, he's simply referring to the disastrous effects on the timeline.

In the Biffhorrific timeline, the Internet as it is today does not exist.

Simply enough, most corporations that form the Internet are in California, which also turns out to be the state in which Biff Tannen and his heirs ravage. (This is implying that in the rest of BTTF2, the Internet exists and is simply never seen, as it would require an entire scene.)

• This would only apply to the future of the timeline- for the bit we see in BTTF2, it's 1985, when most people hadn't heard of the internet in reality.

The Marty and Doc of most of BTTF Pt 2 are insane. Their delusions just happen to be right.

Given: Had Marty failed to make his parents fall in love, he would have endangered all existence by creating a paradoxical world where he was not born and could not have interfered with his parents falling in love.
Given: It is a remarkable coincidence that George and Lorraine had the same three kids with the same three names and substantial, but ultimately inconsequential, differences in their lives (i.e. Dave has a better job).
Given: We must eliminate the fact that Marty and Jennifer simply grew from age 17 to 47 and had two kids between 1985 and 2015 in the timeline in which Marty Sr poses as Marty Jr, because it is impossible, therefore another explanation—however improbable—made it possible for it to appear that they did.

When Marty and Doc travel back in time to 1985, they find themselves in an alternate reality where Hill Valley is a miserable Hell Hole. Okay, but how on Earth did Marty & Doc get ahold of a flying car time machine in the first place? How could they remember a past that Biff had already erased? Why were they in 2015 to begin with?

Remember that the "alternate" 1985 was the product of an alternate 1955 created by Biff. An alternate 1955 by which Doc Brown had still conceived of the Flux Capacitor, and in which George and Lorraine had still been fixed up by "Calvin Klein," followed by an alternate 1968 in which Marty and Jennifer were still born and an alternate 1972 in which George was murdered and Doc was committed. It just, for some reason, involved traveling to 2015 where Marty & Doc were dragging Jennifer into the time machine he piloted.

In this history, suppose Doc was released from the mental hospital at some point prior to 1985 and that Marty's hatred of his stepfather (perhaps even his suspicion that he'd killed his real father) had driven him into a mental state that was fragile, but that Biff—being a jerkass—simply would have just seen as lazy and stupid. It's consistent with Marty sending Biff to Switzerland. A neutral country where people have bank-accounts to avoid taxes or however it works. Maybe Doc would flee there to avoid a stigma he might have in the U.S. but not there. Perhaps his brilliance would permit him to work in a fancy private school and Marty is his student.

That may sound farfetched, but the films aren't exactly clear on the circumstances in which Marty & Doc met in the first place anyway.

Okay, so Doc builds a version of the time machine because he has this strange delusion that Biff somehow got his paws on an almanac from the future that helps him win bets. After-all, if you look closely, there's a picture of him where he's got an almanac from the future tucked away in his pants. Doc learns of Marty's connection to Biff and influences him to buy into his "crazy" theory.

This involves building a time-machine identical to the one we all know and love, complete with the flying. Okay, but how? I dunno, they somehow manage to get aboard a plane with falsified documents. Remember, this is taking place over a period of time prior to October 21, 1985. They could have met as early as 1982 if Marty started the private school at age 14. Anyway, they arrive at Doc's dilapidated mansion, buy a DeLorean and build the thing using his old designs for the FC. The important thing is that the have it completed by October 21, 1985 and take their journey on that day (otherwise, their decision to return on that day becomes a little arbitrary and Biff doesn't end up traveling back in time on that date anyway). Oh, and they've somehow convinced (or forced) Jennifer along. Why? Part of Doc's delusion. How? I don't know. She could also be a troubled youth. Now, at this point, the story of Marty trying to save Marty Jr from joining Griff's gang doesn't matter. ALL that matters is that Griff ends up with the almanac on that day, and decides to go back in time on that day to that very day of November 5, 1955 (a day during which, Marty and Doc's delusions lead them to believe that Marty is supposed to take Lorraine to the dance, etc) and Marty must blame himself for having the idea to make money off of the almanac. In fact, driven crazy by all the crazy stuff going on, maybe Doc's managed to convince Marty that George is still alive. Almost forgot: it's also important that Biff lives until 2015. So when he leaves the DeLorean in pain, and he's fading away? Um... yeah, aliens got him.

So anyway, on October 21, 2015, they find that Biff is frequenting the Café '80s (or whatever it might be called) and he overhears them talking about the time machine. They're talking blatantly so that he can hear them. By this point, Marty had bought the almanac. Here's the disturbing part: they've tied Jennifer up in such a way that it'll be easy for her to escape once they get to the Lyon Estate. They leave the DeLorean open for Biff to steal after she's escaped and once she escapes to a nearby house, they flog her and bring her back. Why? I don't know, but there's Unfortunate Implications. Remember, though, it doesn't even have to be the McFly house.

So Biff steals the car and gives it to himself, leaving the time loop mostly the same. The emotions he's feeling might be different, but his actions while he's there are almost identical. The timeline up to Oct 21 is virtually identical to what I described. Marty & Doc's delusions are the same. They head back and Marty is genuinely surprised by the world around him, not because he remembers it first hand, but because Doc had been working him. Making him think he remembered it. Not through some gizmo that changes peoples' minds, but because he's just that manipulative.

Marty and Doc go through everything we see in the movie with Marty's delusions and Doc's influence on him. Everything we see in the film happens, which means that once they end up in 1955, they create—yes—a new timeline in which the stage was set for the history established by the end of the first film. Their delusions become true. Marty really was raised by George from 1968 to 1985. He really did have a girlfriend named Jennifer. What he thought he knew, he really did know and so the film was compiled from three different timelines.

In the Back to the Future universe, or at least the 2015 timeline shown in the second film, Laserdiscs achieved mainstream popularity in America.

Contrary to another WMG above, the discs shown trash-compacted in the back alley definitely include Laserdiscs. In Real Life they were very much a niche market product in the West, but for them to be thrown away in such significant quantities would imply they would have to have a popularity at least akin to VHS (notoriously difficult to get rid of in Real Life) if not greater. So, either they were popular to begin with (we just never see the fact on-screen) or the experienced a sudden jump in popularity in the 1990s.

In 2015, Jennifer is a shoplifter.

When she returns home, she looks around as if to make sure nobody is looking as she carries shopping bags.

Or, she's a compulsive shopper.

Which would produce a similar reaction- she's hiding her addiction from her family.

Marty and Jennifer's kids are clones.

Jennifer was unable to have kids, so they used future technology to clone Marty. Technology was not advanced enough to combine genes of two people, so the daughter was a Marty clone with its gender changed. Jennifer did not want a clone because she believed that she would faint if she ever saw someone who looked exactly like her.

CusCo is SkyNet in an alternate timeline.

When Ito T. Fujitsu tells Marty, "You are Terminated!" he really means that a Terminator is on its way to kill Marty. In the timeline of Terminator Salvation, there are T-600s by 2016, so maybe that is what would have been sent.

Marty's new personality in the altered timeline was responsible for his kids.

In alternate 1985 Marty is the son of rich, successful, cool parents. This causes Marty himself to become stuck up and spoiled, which is why he now can't stand being called chicken. Being a spoiled kid he expects life to cater to him and hand him all his shit on a silver platter. Then he gets in the car crash and breaks his hand and grows up to become a shlub. Now bitter and resentful he does what a lot of bitter and resentful parents do, he berates and belittles his kids. This causes his son to grow up to become a wimp he is bullied by Griff into committing a crime, Marty Jr. is thinking about doing it mainly to prove his dad wrong.

The 2015 Jennifer was cheating on Marty.

In that future where Marty became a bitter shell of the man she loved (not to mention the shitty wedding and the way he treats their children) has led Jennifer to look for love in other places. It would certainly explain why Marty would have a hard time keeping track of her, as well as his sarcastic comment of how they were like a couple of teenagers. Jennifer's guilt of the affair has led her to being a tranq.

• To add insult to injury, she could be cheating on Marty by having an affair with Needles.

Marty and/or Doc had something to do with Lady Diana's infidelity being exposed

After the second movie, they did some time travel that somehow caused her to be exposed. If not for that, Prince Charles wouldn't have divorced her and she wouldn't have died from a car crash.

Several fans will be watching the second movie on October 21, 2015

That's the day Marty and Doc went forward to. Fans everywhere want to compare the writers' predictions to what really happens. Most of them want to see if, contrary to their expectations, Queen Elizabeth II will be around.

• Pretty much confirmed. It's not even October yet and a lot of cinemas are already advertising special screenings of the trilogy on the 21st.

Charles is dead in the 2015 from the second movie

Some fans ask why "Queen Diana" would go to Washington without her husband. It turns out he died at some point of history between becoming King Charles III or King George VII and 2015. He must have become King otherwise his Princess consort would never become Queen consort.

• This is would mean she's actually the Queen Mother, with William (presumably) being king.

Corporate management in 2015 takes on the corporation as their surnames.

That explains "Fujitsu-san" as Marty's boss. Management at General Motors, for example, would be called Mr. or Ms. General Motors.

• Jossed as the company they work for is called CusCo, not Fujitsu.

Marty jinxed the Chicago Cubs by not racing Needles.

In Part II, the Chicago Cubs were shown winning the World Series, while Marty was shown to be a jaded, depressed salary man because he got into an auto accident in 1985 while racing Needles. In Part III, he avoids getting into the accident, thereby erasing that future, so, on the real October 21, 2015, the Chicago Cubs were sadly beaten by the New York Mets.

The 2015 of Part II is the result of an alternate timeline where Power Metal got big in the early 1990s instead of Grunge

More due to the motifs of 2015 than anything else, if grunge hadn't gotten big, clothing and decorative trends would have likely been different. Power metal is simply a placeholder because with a fairly minor point of divergence, it might have happened.

The Miami team that lost to the Cubs in the 2015 World Series were a relocated Cleveland Indians.

When Marty sees the result of the 2015 World Series, he's stunned that the Cubs won it — but even more stunned that the team they beat was from Miami, which didn't have a major league franchise in 1985. But in "our" timeline, Miami did eventually get a team — the Miami Marlins. Except they play in the National League alongside the Cubs, so they couldn't face each other in the World Series. Instead, we'd have to find a timeline in which Miami has an American League franchise.

As it turns out, in Major League, the plot centers around the attempts to stop the AL's Cleveland Indians from moving to Miami. So, we can assume that in the Back to the Future timeline, the Indians did move to Miami, and that's where they got their AL team. They then went to the World Series in 2015, but lost to the Cubs (of all teams). Interestingly, in "our" timeline, the Cubs didn't win the World Series in 2015 — but they did win it in 2016, and the team they beat was... the Cleveland Indians.

There's also a bit of a Butterfly Effect in this timeline. In "our" timeline, the Cleveland Indians never left — but the NFL's Cleveland Browns did leave, a move which so crushed the city of Cleveland that they immediately built a new stadium for the Indians to keep them from leaving. Presumably, if the Indians left first, then the Browns would have stayed — and the chain of franchise shifts in the NFL in the 1990s could well have been very different.

Marty's car accident somehow prevented the Lost Decade, ensuring that Japan Takes Over the World

When Marty didn't crash into the Rolls Royce, his altered life somehow ended up affecting the Japanese economy, preventing the high-tech Japanophile 2015 of their timeline and replacing it with our own 2015.

Needles set Marty up in a sting operation.

• Just as Marty ends the call with Needles, Needles is smirking at someone off-screen, like he's saying "We got him!" A few seconds later, Mr. Fujitsu, Marty's boss, calls to fire him.
  • Even worse. . . Needles knew exactly how to press Marty's Berserk Button (since it's shown in Part III that he's the one who got Marty into the accident in the first place, using the same tactic). Marty wouldn't have done anything illegal except that Needles set him up for it, probably deliberately.
    • Which makes you wonder, how much of a sociopath would Needles have to be to get a guy into a terrible, disabling accident and not only not care, but continue to take advantage of that person?
  • Why does Needles need Marty to take part in the scam? To test whether the boss would find out. Needles likely hadn't taken part in the scam and needed somebody else to do it first to see how things turn out, and he knew of Marty's berserk button.
  • Considering how often people keep pressing Marty's berserk button, it wouldn't be too far fetched that someone else could get Marty to do something illegal by pressing it. If the sting operation theory is true, Needles could have pressed it to see if Marty would fall for it, since the motivation of solving his family's financial problems didn't get him to take the bait. If anything, him falling for it makes things even WORSE for Marty, since he wouldn't do it to help his family, but for his own selfish wounded pride.

Queen Diana still divorced Charles in Bttf II

She was called "Queen" because people wouldn't acknowledge anybody else as Queen of England in a timeline where she's alive during Charles' time as King.

Marty Junior saw his father as an Anti-Role Model

He grew up hearing about how Marty Senior ruined his life just because he doesn't like being called "chicken" and saw how that incident wasn't enough to put an end to that mentality and decided he was better off being a chicken.

Old Biff realized Calvin was Marty.

That's one of the reasons he chose November 12, 1955 to be the day he gave the almanac to his past self. Knowing how Doc was afraid of a meeting of the selves, he hoped Doc and Marty would never try to recover it in that very day even if they knew that was the day he visited.