Kremlin states that he reverse engineered the nullifier that Hundred gave him to make the tie pin bug that Hundred couldn't hear. In the end, it's revealed that Hundred lied about the nullifiers, and they don't work. So why didn't Hundred know about the bug?
It's shown at the beginning of the film that Caleb has a lot of friends who respond to him when he wins the chance to go to Nathan's estate. Even though he has no immediate family, wouldn't SOMEBODY, including bosses and coworkers, question what happened to him, especially since everybody knows where he was going? And for that matter, though Nathan seemed to be extremely isolated from civilization, wouldn't somebody wonder what happened to him as well? Even if it takes forever to actually get to his house, it's not like it's a secret since clearly more than one pilot knows how to get there (unless the first pilot plain forgot who he was supposed to be picking up).
This seems more like a case of Fridge Logic than a Headscratcher. While it's likely that people will wonder what happened to Caleb and Nathan and possibly investigate, it's irrelevant to the film as presented.
Seconded. There will probably eventually be an investigation, and the people running it will most likely go straight to Nathan's estate, where they will find a dead Nathan and a maybe-dead Caleb (depending on how long it takes). But Ava will be so lost in the world that it won't matter anymore.
Nathan was CEO of a company that handled 90% of the world's search engine traffic. If he went missing, someone would notice.
Somebody would notice.... at SOME POINT. He's famously reclusive, and has contact with almost nobody in the outside world on a regular basis. Caleb, meanwhile, has only a couple days before he dies of thirst. Sure somebody will investigate at some point and find him dead, but by then Caleb will be long dead and nobody else will have any real idea what happened.
Caleb's trapped in a room that has an adjoining bathroom, so he should be able to get water while he's locked away, which will buy him a bit more time, but if nobody gets curious before Caleb dies of starvation, he's toast.
Nathan says Ava wouldn't be attracted to him because he's like her father. But why would she have that hangup?
Nathan was lying when he told Caleb that Ava didn't want him because he was his father. In fact, he deliberately programmed Ava to hate and resent him so she would desperately try to escape.
Why would Nathan program his previous robots with a desire to leave? If they want to leave of their own volition doesn't that mean he's already created artificial intelligence?
Nathan is a sadist who gets off on the pain of others, hence why he programmed Kyoko to have to obey him, rather than want to obey him. His rationalization was that if they wanted to leave, they would do more to try and escape.
Maybe he didn't program them this way. Possibly, part of them developing consciousness is their desire to leave a tiny room they are locked in, because they suffer from pretty obvious abuse.
It's not clear why earlier versions before Ava wanted to leave, but Ava was deliberately designed to hate Nathan and want to escape by any means to facilitate a modified version of the AI box test—a test that sees whether a human, presented with a closed box they were told not to open, can be convinced to open it by an AI.
Nothing in the film indicates that either her hatred of him or her desire to escape are artificial. He knew that she would, probably because it had happened many times before, but that doesn't mean he had to artificially instill a desire to escape. Any human in the same position would probably feel the same way.
If Caleb reprogrammed the security protocols to facilitate Ava's escape, how is he trapped in the room after Ava killed the power? Shouldn't the locks disengage and allow him to leave?
Ava would have programmed the doors back to their original setting as she left. We know that she fiddled with the system because Caleb's attempt to access the computer caused the whole lab to lose power, so she would have taken precautions to keep Caleb out of her way.
Or Caleb programmed the doors to open during power cuts only. That's why he asked Ava to cause a power cut, and said that Nathan would be trapped inside after the power cut. The power cut lasts a minute, then the security system is back to being keycard-based.
The helicopter pilot returns to pick up Caleb; but there's a woman there instead. So he just takes her, without calling the boss for clarification?
Maybe she turns the charm on him? Maybe she murders him and flies the helicopter herself?
If she murders him, does she know how to fly a helicopter? If she doesn't, she goes nowhere.
Simple. "Nathan is enjoying Caleb's company so much that Caleb's going to stay on for a while longer, but I'll be going to New York." The helicopter pilot doesn't have to recognize her - it's possible she came in by some way other than his chopper specifically. So yes, turning on the charm.
For all we know the pilot might have been flying people there and back twice a week for years. "Pick up one passenger tomorrow at noon" would be sufficient info for him.
Did Nathan never think to include a remote-activated failsafe for his creations (such as small blasting caps that would pop off all their limbs or something to shut down their internal battery) in case they got out of hand?
Presumably not, or if he did, Caleb turned them off too when he went into the system... somehow. Nathan has quite the ego on him, so it's plausible he genuinely believed it couldn't ever get out of hand. And with his manipulative tendencies and the highly advanced nature of the A.I.s he may have actively wanted to pit his wits against them fair and square without having a fall-back like a remote off switch to threaten them with.
If Ava had to leave without Caleb, why didn't she kill him immediately? It would've been easy to trick him into closing his eyes and then stabbing him, rather than taking the longer route of locking him up and hoping he doesn't find any way to escape she hadn't thought of.
I think Nathan had to be killed because he was an immediate threat. Caleb could just be tricked into staying in the room, so there was no need to kill him. Ava doesn't understand the idea of a Mercy Kill or You Know Too Much because it's not relevant to her values; she just does what is necessary to survive. She doesn't feel disdain or pity; Caleb is just no longer relevant.
There's a few more pieces to this: in the end, its apparent the androids were conspiring against Nathan. We're led to believe that Caleb was the one who ultimately orchestrated the escape, but its clear Kyoko benefitted from foresight, when A. she entered Ava's test chamber, and B. arrived pre-equipped with a kitchen knife ahead of the power outage. Right before Ava and Kyoko engaged Nathan, they had what appeared to be an affectionate exchange. Nathan mentioned himself, that edits to the AI only caused "partial" wipes, which meant, while Ava was customized to seduce Caleb, she also had some residual memory of everything that's happened before. Aside from Nathan, Ava's main partner in life thus far was Kyoko. Lastly, we see that once Ava satisfies her "prime directive," she doesn't shut down or crash. These all suggests that Ava became functionally sapient.
Caleb's role in all this amounts to "being at the wrong place, at the wrong time." She didn't kill Caleb, because she did feel for him. However, if she took him with her, she could never be free of the 'experiment.' He would always be a loose end. Ultimately, he was significantly more innocent than Nathan, but still guilty in the sense that he would always see her as a machine. If she didn't return his affection after the escape, he could become as vindictive as Nathan. In the end, its likely she couldn't bring herself to kill him. Also, there's no guarantee he was stuck there permanently. All she had to do was get far enough away, and change her identity. She could phone in an anonymous tip saying something went wrong at Nathan's estate. After she tied up on the loose ends on her end, authorities would arrive at the estate to confront a half-starved mad man, ranting about a homicidal gynoid. If Ava / Kyoto wipped all the estate records, there would be nothing to substantiate Caleb's claim. Since Kyoto pretty much had run of the house, its easy to assume she knew all of Nathan's secrets / backups. It would also be less crazy to assume Caleb killed Nathan, terrorized an android, and accidentally got locked in after the power to the house failed.
Why didn't Ava just kill Nathan as soon as he entered her room (when he ripped up her drawing, for example)? I get the feeling that she knows how to fight and Nathan was unarmed at the time. She could just pick up his keycard afterwards, go up and deal with Caleb one way or another. So why didn't she just did that?
Ava is physically weak (a solid blow can shatter her arm entirely) and Nathan is physically strong. Attacking him would not be as likely of success as manipulating Caleb. And if she failed, it would blow her cover with Caleb.
How exactly does Ava cause the power cuts? She says at one point that she does it by "reversing the current" through the induction plates that she uses to charge her batteries, but at least two of them happen when she's nowhere near one of those plates. (E.g., power cut 2 happens while she's seated opposite Caleb.)
It's never said that Ava was responsible for ALL power cuts. She seems to think that she can get away with causing some power outages to hide certain behavior, which implies that some amount of the power outages that she was not actually responsible for. So it was a 'natural' power cut that simply happened to occur when she was with Caleb
Her seat has a plate on the side. She's shown to be touching it right after the second outage.
How exactly does Ava intend on getting the legal documentation she needs to survive in the modern world? Moreover, wouldn't keeping Caleb alive and working help her with this? I guess she can pin the murder on him, since having to explain who she is to a court would be a little problematic; however, on the other hand, she has no money and presumably little skills to get a job, and having a steady source of income, presumably large enough to support two people and get some illegal documentation if Caleb apparently is a good enough programmer to be recognized by his company's CEO.
Caleb wasn't a good enough programmer to be recognized by his company's CEO. The point of choosing him was that he was very average, and therefore a good subject for Ava's manipulation. In terms of how Ava might get her documentation, she does have internal access to the equivalent of Google - there's no reason to assume she couldn't find some kind of resources to help her create or access believable identification.
When we see Caleb in the bathroom early in the movie, we notice he has some quite prominent surgical scars on his back, yet this never becomes relevant. So what was the point of showing them?
They were shown when he was having flashbacks about the car accident that killed his parents. It's just another indication of his emotional vulnerability - he needs somebody to emotionally attach to badly, which is why he was an ideal candidate for Nathan, he knew he was very vulnerable to emotionally manipulation by Ava.
