What An Idiot / Terminator

The Terminators are supposed to be the smartest androids ever created. Too bad they don’t act like it sometimes.

The Terminator

• The Terminator goes to the Alamo Sports Shop gun store to arm itself up.
  You'd Expect: The shopkeeper not to allow it access to functional weapons and live ammunition at the same time, a basic rule of security that is universally enforced.
  Instead: The shopkeeper is so eager to make a big sale for "home defense" that he leaves ammo boxes all on the clerk table and doesn't realize his client is loading a weapon until it is too late.
  Result: Naturally, the man is murdered right there.
  Gun store owner: (sees Terminator putting ammo into SPAS-12, terrified) You can't do that!
  Terminator: Wrong. (shoots)
• Sarah Connor and Kyle Reese have been taken in by the police after the car chase. While the Terminator has at least withdrawn for the time being, they now have some serious explanations to make to the cops.
  You'd Expect: Kyle to simply explain that, while their actions were extreme, they were desperate—the police already know a deranged killer is after Sarah Connor, who is present and obviously scared, and the Tech Noir club was shot up when he came after her, so any number of witnesses can vouch that she obviously ran from something serious. Kyle just has to say that he was doing what he could to save Sarah's life.
  Instead: Kyle tells the police the same "killer robot from the future" story he fed Sarah that, while true, obviously makes him look like a delusional lunatic.
  Result: Naturally, they don't believe him and keep him and Sarah detained, giving the Terminator time to arrive and thus costing every cop in the place their life in Sarah's defense.
• Sarah and Kyle are hiding in a motel after the police station massacre. Sarah then tries to contact her parents by phone, and her mother answers the call.
  You'd Expect: At the very least, Sarah not to give away the motel's phone number. Kyle flat out warned her not to talk to anyone she knows in case the Terminator used it to track them, so even if she's justified in calling her mother to warn her, giving out the phone number was a really stupid move.
  Instead: Sarah gives her "mother" the motel's phone number.
  Result: Said "mother" turns out to be the Terminator mimicking her voice, again on track thanks to her.

Terminator 2: Judgment Day

• Skynet has decided to send a new, much more advanced Terminator, the T-1000, to finish what the previous could not, in a "hail mary" pass.
  You'd Expect: Skynet to send the T-1000 to 1984, back when Sarah and Kyle were being chased by the first Terminator. By doing this, it not only keeps up the surprise factor, but it forms a powerful unit by having two almost indestructible robots teaming up against the already overwhelmed couple.
  Instead: Skynet sends the T-1000 to 1995, a much later date that has no special significance. By this time, John is already a boy old enough to take care of himself, his mother has undergone combat training, and both individuals are aware of Skynet and its Terminators, eliminating all the surprise factor. Moreover, the T-1000 will be alone in its task.
  Result: Obviously they couldn't expect the resistance to send a reprogrammed T-800, but sending the T-1000 to when it did was a big factor in its defeat.
• The T-1000 has both of its primary targets locked in a small elevator at the Pescadero Mental Hospital — albeit with the T-800 protecting them, but they're in a confined space.
  You'd Expect: The T-1000 to get enough of a visual on John and/or Sarah to direct a single killing blow and finish up the others later. Barring that, disable the elevator and flow into the car entirely and overwhelm them since it knows it can't be effectively destroyed with the weapons they have.
  Instead: The T-1000 wastes the entire elevator trip stabbing wildly and more-or-less randomly into the elevator.
  Result: The T-1000 only manages to wing Sarah after it gets a better idea of where she is and only flows into the elevator after they've already exited, which leads to their escape.
• The T-1000 is wasting time treating the elevator like an Indian basket trick, the T-800 tells Sarah and John to get down.
  You'd Expect: The squishy humans, who will be severely injured at best if the blades hit them, to crouch out of reach of the omnicidal shapeshifter.
  Instead: They stay standing the entire time (though in the corner), and Sarah even grabs the T-800's handgun to shoot back.
  Result: Sarah gives away her position until the inevitable happens and she gets her back all sliced up. It's only pure dumb luck the T-1000 misses by just enough inches to avoid killing either her or John.
• The T-1000 is giving chase through the steel mill, and wants to attract John.
  You'd Expect: Having already touched two of its opponents (the T-800 in their first fight and Sarah in the elevator) to shapeshift into either of them and call John with their voices.
  Instead: It keeps using its default form, and after it captures the real Sarah, it demands her to call John, even although it can perfectly mimic her voice and has already heard her talk enough to sample it.
  Result: Again, the T-1000 finally thinks on the aforementioned and impersonates Sarah, but only after the previous move has failed.

Terminator 3: Rise of the Machines

• The T-X (noted to have the ability to fight other Terminators) has knocked out the T-800 with its built-in plasma cannon.
  You'd Expect: The T-X to capitalize and then either disable the T-800 completely or infect him with its nano-machines to ensure that it is no longer an obstacle.
  Instead: It forgets all about him, even although the T-X doesn't leave the place either, but stays there waiting for the cops to come to infect their cars.
  Result: Ironically, much later in the film, when the T-800 is knocked out in their second fight, it finally occurs to the T-X to do take control of it.
• The T-X butchers Scott, Kate's boyfriend, and impersonates him in order to tag along the cops and find her.
  You'd Expect: The T-X to retain its disguise after coming face to face with Kate, who is running emotionally to hug him, and tear her heart out. Then, impersonate Kate and do the same with John.
  Instead: The robot returns ominously to its default form in midst of Kate's run.
  Result: This alerts Kate that it's not Scott and makes her stop. The chance is subsequently lost.
• The T-X manages to impersonate Kate and get the drop on her father at the military base where Skynet was created and is currently taking over. Immediately after she arrives, the real Kate arrives along with John and the T-800.
  You'd Expect: The T-X to immediately shoot John and/or Kate, as they're both its highest priority targets.
  Instead: The T-X wastes time shooting Kate's father, who is merely a secondary target.
  Result: This gives the T-800 enough time to shoot it down a ventilation shaft.

Terminator Salvation

• Skynet wants to lure John to its San Francisco base to have him killed, and it knows John is searching for Kyle Reese.
  You'd Expect: Skynet to leak out the fake info that Reese, or someone who might be him, has been captured by the machines and is imprisoned in San Francisco. It is not necessarily a very effective plan, given that what would John do right after is up to many circumstances and it's not likely he would venture there alone, but it is the safest version of the plan.
  Instead: It concocts a weirdly convoluted plan where it activates an unaware Terminator and has him roam around, find the real Kyle, reach John, get him to move, and finally return. Some of those events happen by pure chance, as Marcus was a relatively unpredictable pawn who might have not even found Kyle or gained Connor's trust in the first place, leaving unclear how probable they were in the first place. Even more weirdly, the plan more or less works, and John does venture himself alone to rescue Reese, but the plan's uncontrolled factors come to bite Skynet in the ass when Marcus breaks free from its control, destroys the T-800 meant to kill John and saves his life by giving his heart.
• General Ashdown and his staff are going to mass broadcast a radio signal that will ostensibly turn off all of Skynet's units.
  You'd Expect: Them to broadcast the signal from a buoy, an airplane or any random outpost, anywhere except from their main headquarters. Even if the signal was not a trap, it might not completely shut off Skynet and his army given the possibility of autonomous machines or backup systems, and in that case they would have emitted a signal that could be tracked directly to their high command, painting a giant target on it.
  Instead: They broadcast it directly from their submarine HQ. The signal was a trap, and a Skynet aircraft picks the location and blows the submarine up, killing all of the resistance's commanders.
• Skynet has finally captured Kyle Reese, who is being transported in an aircraft to its base.
  You'd Expect: Skynet to order him to be executed right there. This version of Skynet is aware of the time loop and knows he will be John's father, which is the reason why both John and Skynet were searching for him. By killing Kyle, the timeline is changed and Skynet wins the game regardless of whether it manage to kill Connor in present time or not. Even if this doesn't happen, it is worth a try, as Kyle has no value for Skynet anymore; John has learned from Marcus that Kyle was captured and is heading to the Skynet base as the supercomputer wants.
  Instead: It keeps Kyle alive the whole time (leaving him in a cell and implied to be planning to use him for experiments), which allows him to be rescued and come out alive by the end.
• Skynet finally has John inside its facilities, where he can be killed.
  You'd Expect: Anything at all — Skynet's biggest source of opposition is right inside its building, they know he's there, and even remark upon this to Marcus. They should be activating every tool at their disposal, regardless of whether it's a stationary unit or some other part of the building's defences, to impede or kill him. Literally anything that ensures its most dangerous enemy is dead for good.
  Instead: Skynet sends a single T-800, unarmed and naked, to fight John. Though he does rough John up a bit, it fails to kill John and is destroyed.
• John is running from a T-800 he knows can imitate voices and hears the voice of Kyle, who he knows is no longer in the area.
  You'd Expect: John recognizes an old Terminator trick and approaches warily, if at all, getting eyes on the situation from a distance.
  Instead: John rushes over and runs straight into the T-800 at point-blank range.
  You'd Also Expect: John, who was trained during his childhood and spent the years since Judgment Day fighting Terminators, to be prepared to withdraw quickly and safely.
  Instead: John pitches himself bodily over a railing and lands badly, injuring himself.
  Result: The T-800 knows where John is, John is barely mobile, and John winds up impaled by the T-800 not long after.

Terminator: Genisys

• The second T-1000 has made contact with Kyle Reese, who just arrived from the future and is fleeing from the cops.
  You'd Expect: The T-1000 to just wordlessly behead Kyle on the spot, capitalizing on his disorientation and the fact that he doesn't know he's in front of a Terminator.
  Instead: The T-1000 stops and utters an ominous, prescient line, and morphs its arm into a blade before actually attacking Kyle.
  Result: Kyle is alerted that something is wrong, and then Kyle spots the blade, so he manages to dodge the slash and run away.
  Adding to the stupidity: In T2, the T-1000 never showed its blade before attacking — by the time it was out, the target was dead, and considering how small the lapse was, it probably marked the difference.
• The second T-1000 reactivates the disabled T-800, leaving Sarah, Pops, and Kyle to deal with two Terminators at once.
  You'd Expect: Both of them to attack either Kyle or Sarah together, as without even one of them, John Connor can't be born.
  Instead: The reactivated T-800 chases down Kyle and the T-1000 goes after Sarah.
  Result: Kyle manages to destroy the T-800 and Sarah and Pops' trap for the T-1000 takes it out as well.
• By Kyle's insistence, he and Sarah are going to travel in time to 2017 to stop a new form of Skynet named Genisys.
  You'd Expect: Them to set the machine to travel forward to 2016. They will have an entire year to adapt themselves, rest a bit, and develop a plan to discover what is Genisys and what is the best way to stop it. True, the T-3000 might have been already around, but none of them knew that, and it would have been still a better situation for them than meeting him while chained in a hospital.
  Instead: They travel forward to 2017, a day and a half before Genisys is activated.
  Result: They get soon involved in a rushed countdown in order to stop it and save humanity, which they barely do.
  You'd Also Expect: That Pops, having helped to build the Cyberdyne base, found some way to sabotage it or making their mission easier.
  Instead: He does memorize the place's map, but only that. He effectively helped to build the place where their enemy will be born.

Terminator: Dark Fate

• In the film (a direct sequel to Terminator 2: Judgment Day, Skynet sends multiple Terminators back in time to kill John Connor.
  You'd Expect: That since neither of their plans worked (the attempts to kill Sarah Connor in 1984 and John in 1995 failed), that they would send multiple Terminators to the same point in time or in close succession so they can work together. In this continuity, T2 made it clear that Skynet already knew it had failed by the time it sent the T-1000, which was a "hail mary" pass.
  Instead: Skynet does not do any of this, instead deciding to send T-800 models one at a time, with multi-year gaps between them. By the time Skynet has done so, Skynet itself has been destroyed and units are simply being chucked through with no discernible purpose.
• "Carl" (the T-800 responsible for ambushing and killing John in Guatemala) has completed its mission and has no further orders.
  You'd Expect: That since he is still a creation of Skynet and should still take pains to either conceal or eliminate his own existence (as the T-800/"Uncle John" did at the end of T2), he would either go to a secluded place and hide (so as not to interrupt the timeline) or take other actions to benefit Skynet's agenda.
  Instead: Due to Skynet inexplicably placing a command in all of its units that functionally allows them to continue learning (via putting them in "independent" mode), Carl comes to realize that killing John was All for Nothing, gains a conscience and even becomes a successful businessman, and decides to start helping Sarah Connor as a shadow benefactor by giving her the heads-up on incoming T-800 units. By the time Sarah, Dani and Grace reach him in Texas, he's amassed a stockpile of weaponry and is all but jumping at the chance to help them defeat the Rev-9.
• The Rev-9 is chasing the heroes on the highway in a dump truck. Grace leaps onto their pickup's bed and grabs some steel rebar to use them as makeshift javelins.
  You'd Expect: Her to target the dump truck's wheels or engine block, disabling the vehicle and forcing the Rev-9 to waste time procuring another, buying them time to widen the distance between them and hopefully cause it to lose track of them.
  Instead: Of the six she has in the bed, she throws four in an attempt to damage the Rev-9, even though it's as fast as she is and most its body will not be damaged by chucking lengths of rebar at it. The fifth and six are used to target the engine and wheels, respectively.
  Result: By this point she's wasted too much time, allowing the Rev-9 to separate its liquid metal half to jump onto their pickup, disabling it by damaging the tires. Furthermore, the move also hands the Rev-9 its own throwing weapons by grabbing one of the rods and throwing it back, killing Diego when Grace deflects it from hitting Dani.
• The Rev-9 infiltrates the border station where Dani, Sarah and Grace are being contained. In order not to be discovered, it shapeshifts into a female agent.
  You'd Expect: The Rev-9 to keep the disguise up, which will allow it to catch them off guard.
  Instead: For no explicit reason, it returns to its default form right after entering the station, which gets it immediately noticed by the women once they are face to face again.
  You'd Also Expect: The Rev-9 to use the base's staff in its benefit during the women's escape. It has already done exactly that twice, first pretending to be a commander to order the heroes to get arrested at the border and later to enter the building dressed up as a male agent.
  Instead: Again for absolutely no reason, the Rev-9 starts stabbing guards left and right while pursuing the women during the brawl. This both deprives the Rev-9 from potential allies in its task and makes it lose a crapton of time, as the act invariably attracts the attention of other guards and they throw themselves at the android in a rather admirable attempt to stop it. When the Rev-9 manages to shake them off, the women have had just enough time to aboard a chopper.