WARNING: Spoilers are unmarked.
- The full reading of Doc's letter (which was started at the end of Part II but never finished), especially since it was intended by Doc to be the final words he ever said to Marty. Marty and 1955 Doc even get choked up reading it, with the latter commenting "I never knew I could write anything so touching."Do not, I repeat, do not attempt to come back here to get me. I am perfectly happy living in the fresh air and the wide open spaces, and I fear that unnecessary time travel only risks further disruption of the space-time continuum. And please take care of Einstein for me. I know that you will give him a good home. Remember to walk him twice a day, and that he only likes canned dog food. These are my wishes; please respect them and follow them.
And so, Marty, I now say farewell and wish you godspeed. You've been a good, kind, and loyal friend to me. You've made a real difference in my life. I will always treasure our relationship and think on you with fond memories, warm feelings, and a special place in my heart.
Your friend in time,
"Doc" Emmett L. Brown
September 1, 1885- The 1955 Doc's shock when he sees that his future self has instructed Marty to destroy the time machine after returning to 1985. Remember, during the first film, he said "I've finally invented something that works!" when he was shown the time machine, and was thrilled when the plan to send Marty back to the future has succeeded. And now, to find out that his great invention has to be destroyed for reasons that Marty never gets to share has to be crushing for him.
- Copernicus whimpering at 1985 Doc's tombstone. Somehow, the dog knows it means something bad happened to his human.
- A Deleted Scene shows Marshall Strickland get gunned down by Buford, right in front of his son. He dies on the spot. It was actually for this reason the scene was taken out, though the event has been confirmed as Canon, at least according to the game (in the comic series, Marshall Strickland is still alive in 1893).
- What winds up being a key factor in Marty learning to let go of his "chicken" aggression? Seamus' story about his brother who coincidentally was named "Martin." Like Marty, Martin had a habit of being provoked into fighting since he felt that he couldn't let anyone think he was a coward. Had.Seamus: That's how he got a knife shoved through his belly in a saloon in Virginia City. Never considered the future, poor Martin. God rest his soul.
- The significance of Seamus telling Marty the story? Marty let Buford provoke him into taking part in a duel on Monday, and Seamus couldn't help but notice the similarities.
- Also, right after Buford calls Marty "yellow", baby Will starts crying, as if he knows what Marty is about to do.
- Another factor is Doc accidentally blurting out to Marty that he'll get into an accident in the future because of his character flaw.Marty: Doc, what is wrong with my future?!
Doc: Marty, we all make decisions that could affect the course of our lives. You do what you gotta do, I'll do what I gotta do. - Fortunately for us all, Doc's vague warning was not lost on Marty, and it's this conversation that makes him finally realize what a dangerous path he's put himself on if he doesn't let go of his pride.
- Any scene with Doc and Clara within thirty feet of each other that is not a Heartwarming Moment is bound to be a Heartbreaking Moment. Case in point: Clara demands to know why he would make up such an elaborate lie about traveling to the future when a simple "I don't love you" would suffice. Then she slams the door in Doc's face. Cue Doc's big brown puppy-dog eyes filled with pain when he says to the shut door, "But that's not the truth!" He told her the truth because she asked for it, but the truth is so outrageous that she could only see it as a lie. Selling it even more: Doc walks away sadly after placing the flower he meant for Clara on her bedroom windowsill. Meanwhile, on the other side of window, Clara flops across her bed in tears.
- And that whole scene doesn't even start the pain train. What starts it is the scene before it when Doc tells Marty that he at least has to tell Clara goodbye. When Marty McFly, the guy who flies off the handle at being called "chicken," has to be the voice of reason, then you know Doc's in a fucked-up headspace.Marty: Come on, Doc. Think about it. What are you gonna say to her? "I gotta go back to the future"? I mean, she's not gonna understand that, Doc. Hell, I'm in it with you and I don't even understand it. Doc, listen, maybe we can take Clara with us.
Doc: To the future? You reminded me, Marty. I'm a scientist so I must be scientific about this. I cautioned you about disrupting the continuum for your own personal benefit, therefore I must do no less. We shall proceed as planned and as soon as we return to 1985, we'll destroy this infernal machine. Traveling through time has become much too painful.- Even before this, as Doc is leaving after escorting Clara home after rescuing her from the ravine, a throwaway comment by Marty makes him realise that the woman he saved and is now smitten with was destined to die in that crash, and he has now potentially radically altered history much as Marty and Biff did before him. Marty tries to dismiss it but a sobered and glum looking Doc says "I wish I'd never invented that infernal time machine. It's caused nothing but disaster." Seeing Doc so thoroughly disillusioned with the object of his life's work and slowly realising that he has fallen in love at first sight despite his earlier protestations, is incredibly tragic.
- And that whole scene doesn't even start the pain train. What starts it is the scene before it when Doc tells Marty that he at least has to tell Clara goodbye. When Marty McFly, the guy who flies off the handle at being called "chicken," has to be the voice of reason, then you know Doc's in a fucked-up headspace.
- One truly tragic scenario
suggested by Word of God and noted under the "Fridge Horror" tab, is that in the timeline where Mad Dog Tannen shot Doc in the back after he saved Clara from the ravine, Doc lingered on for two days in a deeply painful and humiliating state before passing away despite Clara's attempts to nurse him. It's not hard to imagine the both of them wishing they had a lifetime together... And then a week after his burial, Clara purposely jumped into the ravine Doc originally saved her from, ensuring it would become Clayton Ravine anyway. - Doc initially plans to remain in 1885 with Clara but realizes that given his own constant lectures to Marty about not interfering with the space-time continuum, he had better take his own advice. He goes to her house to break up with her but ends up bending his own rules when she insists on an answer, telling her about the time machine. When she doesn't believe him and kicks him out, he wanders off to drown his sorrows, insisting on whiskey even though the bartender tries to warn him off it ("You remember what happened to you on the Fourth of July?") The next time we see him, he's flatly telling everyone in the saloon about inventions in the future. We're supposed to take it for granted that he's drunk out of his mind, but it's quickly revealed that he hasn't even had the whiskey he's asked for and is just cradling the shot glass in his hand. It's very much Played for Laughs, but considering that he becomes practically comatose after one shot—and that he clearly knows this, given the mention of the Fourth of July incident—there's an almost suicidal overtone in the gesture with which he downs the glass after Marty arrives to bring him back to 1985.
- The shot where Marty realizes the train is speeding towards him is about as sad as it is terrifying. The Grim Reaper has tried to come for Marty so many times in these movies, and all three of them have happened back to back, which means he hasn't had much time to rest and recover in-between these incidents. First, he was shot at by terrorists and watched his best friend get murdered by them. Then Biff almost ran him over with his car in 1955. Then he was almost erased from existence, then got to experience being struck by lightning during a dangerous plan to get back to 1985. Then he was accosted by Griff and his goons in 2015. Then he was almost killed by numerous people in 1985-A while dealing with the guilt that his greed got his father killed. Then 1955 Biff tried to run him over with his car again. Then Buford tried to hang him in 1885 and would have succeeded if Doc hadn't stepped in. Then he had a showdown with Buford where at least one of them was fighting to kill. Then he nearly flew off a cliff during another dangerous plan to get back to 1985. Then, just when he thinks it's all over, he has to haul ass out of the DeLorean in about twenty seconds to avoid getting obliterated by a freight train. How much trauma can one teenager handle, even a super-resilient one like Marty, before it catches up to him?
- The DeLorean's destruction. Seeing one of the most iconic props in cinema get wrecked after it has gone through hell and back, and just keep ticking is heartbreaking. The worst part is seeing the flux capacitor and the time interface go out. That Cool Car was practically a character in its own right. A more faithful vehicle you couldn't hope for, and it was smashed to smithereens like any other piece of junk. While Doc has repeatedly regretted building it and wanted it destroyed as soon as Marty returned to 1985 (with or without Doc himself), and while Marty knew this, it was still really hard to take after everything Marty (and the viewers) went through. Watch.Marty: [Choked up] Well, Doc... it's destroyed... just like you wanted.
- Furthermore, the shot showing the time circuits and flux capacitor fizzling and dying. The analogy of a heart monitor flatlining.
- While Marty getting momentarily trapped inside the DeLorean as a train speeds towards it is Nightmare Fuel, it's also saddening. It's like the DeLorean didn't want to "die" alone.
- What really sells it is that, from Marty's point of view, this isn't just the death of the DeLorean, but the thought of never seeing Doc again. He's still in 1885, and although he would leave him with Clara in his arms and the likelihood of a happy future in front of him, from Marty's perspective, Doc is still long-dead (at least not killed by Buford Tannen) , and the Time Travel option is cut off permanently and Marty will never see him again. Or so it seemed...
