Mystique is disguised as a US army colonel when she goes to Vietnam. The colonel's speech patterns and expressions are distinctly odd — intentionally so. 'He' has feminine speech patterns and body language, a sign that Mystique is still somewhat inexperienced acting as someone of a different gender. She makes a similar mistake when impersonating Trask. She compliments his secretary's clothing, which seemed to be out of character based on the secretary's reaction.
Many fans found it nonsensical that Charles and Mystique apparently grew up together in First Class, and that the kind-hearted but broken Raven of the past is so different from the murderous, bitter Mystique of the original films. As Future!Charles explains, after Raven killed Trask, she was captured and tortured for who knows how long. By the time she was freed (presumably by someone other than Charles) the torture had started her well down the path of becoming the sadist of the original films. She may have even forgotten, or blocked out, the good memories she had of Charles.
The inhibitor clamps on the mutant prisoner's necks in the future contain a neon orange liquid. Just like the serum 1973 Charles and Hank use to inhibit their powers. The Sentinels are using Charles' own serum to pacify mutants.
Why did Bolivar Trask see uniting against mutants as the only way for humans to peacefully coexist? Because both the Cuban Missile Crisis and the Paris Peace Conference already proved that two sides as embittered against each other as the Communists and the Americans would drop their conflict and unite in a heartbeat when a common enemy was sighted. And he had a point. After all, by creating the Sentinels, he caused life-long enemies Xavier and Magneto to join forces and fight the common threat.
It seems a little Out of Character for Charles to suddenly hate and suppress his mutant powers, but consider his situation. Not only was his telepathy affected by his paralysis, but the overall attitude and minds of people around him has probably gotten a lot darker and more cynical. It was most likely much more enjoyable to be a telepath during the more positive early '60s than the negative and depressing early '70s. Not to mention the rather horrifying experience with Shaw and the coin, thanks to his powers. It's also heavily implied that due to his mental state (and maybe his abilities becoming stronger in the decade gap), he can't block out the voices anymore. Previously, he'd had to concentrate to hear thoughts, but now he just hears everyone within a certain range. And since he started hearing them while in an isolated mansion, it's a pretty big range.
It may or may not be intentional by the writers, but Xavier's emotional state in First Class and Days of Future Past works well as a metaphor for America's mindset during the time period the movies depict. In 1962, the character's optimism is an extension of the hopeful outlook President Kennedy's administration tended to exude, whereas Charles' melancholia in 1973 is not unlike the general malaise American citizens felt while under the shadow of the Vietnam War. Xavier's descent into despair began in 1963, which is the same year Kennedy was assassinated—the end of "Camelot" note Kennedy's presidency is sometimes called this parallels the end of Professor X's school. At least in the Alternate Timeline, Charles starts to piece himself together again shortly after the Paris Peace Accords are signed.
There is some question as to how Kitty got her time-travel abilities, but when it came up I remembered that in several other continuities, one of her best childhood friends is one of Marvel's main time-travelers, Magik (Illyana Rasputin). Mage something she picked up from a friend, or at least had some experience to draw upon.
Alternatively, she is still phasing, she's just learned a new way to do it. Instead of phasing people into objects, she's phasing them into themselves at different points in the timeline For a longer explanation see here:note In the comics, Kitty's explicitly and implicitly been able to leave things inside of other things as she phases, usually using it to kill people. In this instance however, she's phasing a person's intangible consciousness (similar to how she can "walk on air" using her phasing powers to phase through intangible gases) through their different iterations, "leaving" the older consciousness inside the younger one. In order to do this, she obviously must pass through the only connection the "past" consciousness has to the "present": all of the consciousnesses between those two points in time. This is why the film describes it as "stretching", and why the subject retains their memories of the future into the past and the altered timeline. Their consciousness is phased through every point in their timeline, pulled like quantum taffy to get to the point in the past where it can be useful. Now obviously with there being a theoretically infinite number of points between two markers on a timeline, the number of consciousnesses adds up fast (hence why it hurts and why normal people can only go back a few days at most, while Logan's healing factor allows his "taffy" to repair itself as it gets stretched). However, this explanation not only fits all the descriptions given in the film, but also justifies the San Dimas Time and Ripple Effect-Proof Memory experienced by the user, because in essence all of the future elements of that person are phased into their past self, rather than merely "emailed" as the description of "projecting his past self" implies.
Alternately alternatively, Kitty is still phasing. She's just phasing through a new medium: Space-Time. In many theoretical models space and time are inextricably linked; for one to travel through time, one must also travel through spacenote The earth isn't a static object. Not only does it rotate about its axis, but it orbits the sun as well. For that matter the sun itself, and even the Milky Way galaxy are all in motion through the universe. If one were to travel through time without traveling through space, one might end up at a time only to find there's no place to be! Kitty already phases through space when she uses her powers, allowing herself to pass through physical objects. Since space and time are interconnected, it doesn't take a tremendous leap to imagine Kitty learning to phase someone through space and time in the 20-odd years since her last appearance in the timeline, rather than merely space.
When wondering why they bothered to free Magneto in the past, isn't it possible Future Magneto might have been secretly hoping for a little redemption of his own in the new Timeline?
Perhaps they didn't just need to stop Mystique from killing Trask. They needed to stop, or at least curtail, the "wasted time" Charles and Erik spent fighting each other. Allowing Mystique to see the better path allows Magneto to as well, perhaps stopping the formation of the Brotherhood of Mutants outright (or at least, hastening Magneto's eventual HeelFace Turn).
Though it might seem like a bit of a cheat to suddenly bring Scott, Jean, and Professor Xavier back from the dead due to the Cosmic Retcon at the end of the movie, all of those changes can easily be explained by one simple change: Mystique apparently prevented William Stryker from capturing Wolverine, which could logically cause a domino effect undoing some major plot points from the first three X-Men movies. Without Wolverine in Stryker's custody, there wouldn't be a Weapon X program, the X-Men wouldn't have had any reason to investigate the Alkali Lake facility, Jean wouldn't have had to sacrifice herself to save the team, and she wouldn't have come back as Phoenix and murdered Scott and the Professor.
Another possible explanation (either separately or in combination with the above): Xavier talking to Mystique instead of controlling her at the end, despite everything at stake, might imply that he talks Jean Grey through learning to control her powers instead of just sealing them away with mind control, meaning the Phoenix personality never existed in the first place.
When Past Xavier saw into Wolverine's mind, he saw how Jean would become Dark Phoenix and that Wolverine would have to kill her. Knowing a few decades in advance that his top student was going to flip her shit probably prompted him to put stronger mental locks and safeguards on her powers, preventing pretty much the entire third movie from happening.
Or since the film takes place before Xavier met Jean, he instead sought her out much earlier than he did previously to make sure he could give her the proper help and training she needed to fully control her powers, so there was no need for mental blocks in the first place.
Another possibility: Xavier is aware of the events at Alkali Lake and that Stryker will be plotting against them and uses the captured Magneto to not only get information about the mansions defenses but also to catch Xavier and Scott. So if things get bad enough that they start repeating (which they might have given Rogue's presence and interference in The Rogue Cut), Xavier could avoid the whole situation by not handing Magneto to the police at the end of the first movie.
Quicksilver doesn't seem to know Wolverine, suggesting that they met in the future, perhaps after the time of any of the previous films. And Wolverine actually confirmed that he only met Peter when the latter isn't so young anymore. Rather depressingly, his absence from the future scenes in Days of Future Past can be explained by him being among the mutants who've been killed off by then.
Even though he hasn't done a prison break before, Peter knows he has to hold Erik's head to prevent whiplash. He might have found out from a dry run with Wolverine. Ouch.
Of course, Logan is a history teacher. He's probably the best person to give lectures on American history, having lived through most of it and presumably Stryker never had the chance to blow Logan's memory via an adamantium bullet in the new timeline, all thanks to Mystique. Either that or Logan still recovered his memory after the events of X2, like normal, and Jean's better control of her powers meant that X3 didn't come to pass due to her greater control. At the same time, perhaps Jean's superior control meant that his memory was able to be recovered without needing the extensive investigation of Alkali Lake like it did in the original timeline.
The excessive, almost sadistic manner in which the Sentinels kill off the X-Men in the future might seem like they Took a Level in Jerkass. However, they've dealt with Wolverine before and know how fast he can heal/recover. To them they've adopted No Kill Like Overkill because that's the only way to destroy a mutant like Logan.
Not to mention, while Logan's healing factor is in a class by itself, there are plenty of mutants that can be Nigh Invulnerable (Colossus, Juggernaut) or just really difficult to deliver a killing blow to (Nightcrawler, Blink), or just raw Determinators who keep fighting to their very last breath and then some (Magneto). Splattering them across the countryside is pretty much The Only Way To Be Sure.
Xavier's bumbling attempt at talking his way past guards in the Pentagon is in stark contrast to how he is usually able to handle people through talking. However, it fits in perfectly when you consider that he has suppressed his telepathy, which he might normally use to work out what kind of persuasion works best on a person.
Human-looking Hank McCoy's cameo in X2 has largely been ignored by fans since a blue and furry Beast appears in X3 and has a history with the X-Men (which is then elaborated on in First Class.) A few people suggested the holographic "image inducer" disguise devices from the comics might explain it, but that never caught on (no such thing has turned up in the movie verse, and the comic largely retired them long ago.) We pretty much applied the MST3K Mantra and said "Obviously they hadn't planned X3 when that happened, just ignore it, it doesn't count." However, the power suppression drugs in DOFP make it quite easy for Beast to have resumed his human form while he was away from the X-Men.
While the film basically Hand Waved Kitty having Mental Time Travel as a New Powers as the Plot Demands (or the All There in the Manual explanation of secondary mutations), there is an interesting rationale: if one assumes that as Kitty's powers or her control over them grows, she eventually becomes able not just to phase her molecules through solid matter (and probably, though it is never seen, to "walk on air" like in the comics) but to phase a mind through time...because it is already known that her powers affect electricity, disrupting it (what are brain waves, again...?) and because as Einstein theorized, space and time are relative.
When Hank injects himself with the Serum, the Sentinel stops registering him as a mutant...because the Serum affects DNA. Given the amount Hank used, he doesn't register as a mutant because he isn't one.
When you read the lyrics of Jim Croce's "Time in a Bottle" (which is about a man who wishes he could save time and spend it with his beloved), it basically reflects the elderly Erik's profound regret when he tells Charles (whom he loves as a brother), "All those years wasted fighting each other, Charles. To have a precious few of them back..."
Xavier calls Peter Maximoff "a pain in the ass" when they first meet. Later on, Wolverine observes that Magneto was "always an asshole." Comic book fans would recognize the subtle Like Father, Like Son connection...
Trask's idea of using Mystique's DNA to benefit his most certainly mechanical Sentinels might sound farfetched, but the idea somehow lasted into the Bad Future, where the "Nimrods" somehow exhibit Emma Frost and Darwin's abilities. One even sprouts claws like Lady Deathstrike.
It makes perfect sense for Hank to be a Trekkie because the ideals promoted on Star Trek: The Original Series are very similar to Professor X's: peace, tolerance, egalitarianism, etc. Beast would very much like to live in a Utopia where humans (and mutants) have overcome their differences and are united as one. Hank even seems especially fond of the character Spock (who is a half-human, half-Vulcanscientist with Super Strength, a situation that Beast can strongly relate to) because he specifically uses the adjective "fascinating" when he first sees Peter's power.
Charles' attempt to talk down Raven at the airport crashes and burns when she throws his words back in his face ("I'm at the house where you should be," "You have to come home,") rebelling against being manipulated by others for their own agendas. This echoes a certain scene in the previous movie where Charles chooses his words so poorly that a dear friend is only further angered by his attempt to talk them down. The younger Charles is apparently very bad with words when he's desperate.
Although Peter asking Erik if he knows karate was an excuse to crack a James Brown joke, it would be natural for the teen to bring up martial arts because Enter the Dragon was released in 1973, which turned Bruce Lee into an international star. Lee's punches were reputed to be faster than what 24-frames-per-second film could capture (and he thus had to be slower when he performed in front of the camera), and Quicksilver would admire a non-mutant (as far as we know!) who could achieve that high speed.
When he shows up to lift the RFK Stadium to attack the White House, Erik doesn't really require the armour chest plating for what one could imagine bullets or knife wounds... but he spent time locked up with guards having plastic guns on them.
1973!Magneto's actions like trying to kill Mystique on sight and then attacking the White House might seem overly extreme (and just plain being a Jerkass)... until you consider his history. The Bad Future where mutants are exterminated or imprisoned is basically The Holocaust on a global scale, and Magneto is a Holocaust survivor. He's already had to live through those horrors once, and to learn that it's going to happen again and worse would be enough to drive almost anyone to desperate measures.
In "Everything Wrong With X-Men: Days of Future Past", they point out that for some reason, Quicksilver's Walkman isn't playing at 1/10th of its speed. Exactly - he modified it to play 10 times faster, like with the Pong cabinet. His jacket and hair don't react at 1/10th speed either, implying that his powers keep his personal effects up to time with him, otherwise the constant starts and stops would wreck the Walkman anyway.
Dwarfism is a genetic mutation, that means Trask is a mutant who is hunting other mutants.
While genetic mutation for Mutants gives them cool powers like the ability to shoot lasers from their eyes, control metal, read minds, etc. genetic mutation for Trask gave him the super amazing power... of being much shorter than everybody else, for which he was likely bullied and ridiculed for his entire life. Even if he's not conscious of it, Trask's vendetta against the mutants can easily be seen as ultimately the result of a deeply ingrained inferiority complex which drives him to prove himself as their superior.
There's another reason that Scott seems offput at the end when Logan tells him it's good to see him. In addition to it being out of character for Logan to be so warm toward Scott, the two of them live and work in the same building. "Good to see you," is just plain odd to say to someone you see every day.
Rogue's power absorbs memories. So, in The Rogue Cut, when Iceman touched her cheek, she got the memories of everything he lived through. So she not only learnt how things have gone to hell after whenever she went under, she finds out the boy she loved is in a serious relationship with someone else, and probably gets some of those memories in the process. Not to mention, absorbing Kitty's powers probably brought some of her memories over as well. Rogue just does not catch a single break.
On the first viewing, it may seem puzzling that Bolivar Trask would be imprisoned in the metal-less prison cell that was until now used to hold Magneto. Since he has no power, an ordinary prison would work just fine, right? And then you realize: the special cell is needed not to prevent Trask from escaping, but to prevent Magneto from reaching him. After all, it is highly probable he or other mutants would be planning to murder Trask in order to avenge the torture of several of their kind, not to mention the whole Sentinels plot.
Aside from "Because it's convenient for writing and makeup" why does Beast's power seem to work like a Hulk out? Because when he gets pissed off his blood pumps faster, cycling the serum out of his system, and he's keeping his medication level on the cusp of transformation just in case he needs to do exactly that.
The film was a very decent homage as well as Deconstruction of the Bronze Age, with the government and large corporations being portrayed as corrupt and evil, but only in the hands of corrupt and evil people like Boliver Trask. The heroes and anti-heroes are disillusioned and harsh towards one another, particularly Charles Xavier, but a good deal of his character development involves him learning to hope and trust again so as to save the future.
Hell, Past Charles entire character arc fits perfectly alongside the events of First Class. Some fans were confused about the ease with which Charles recovered (mentally) from the devastation and loss that he went through at the climax of First Class. It turns out, he didn't. He likely internalized most of his pain, causing him to break completely when he lost everything else.
During the opening monologue, it is mentioned that Mutants, future Mutants, parents of Mutants, future parents of Mutants, childrenof Mutants, Mutant sympathizers, and anyone who got in the way were almost completely either killed or imprisoned by the time of the movie, leaving only the "very worst of humanity" unharmed. The only people left alive are those that share neither sympathy nor genetics with the mutants, and they all stood by and let the genocide of most of the human race happen, all in the name of eradicating the minuscule fraction that they were afraid of. Ironic, considering that the Sentinels were originally designed by Trask (very well, might I add, enough that even if someone has the Mutant X-gene but has no Mutant powers they are not a target, as Hank fortunately discovers) to target Mutants and only Mutants. They Grew Beyond Their Programming and the survivors decided that that was perfectly okay.
Or, even worse, once the mutants started fighting back and the war actually started, the xenophobia shot through the roof and the humans themselves started adding onto the programming. Every subsequent large-scale display of mutant powers would allow them to justify taking it up a notch until the sentinel's targeting parameters would be as broad as they are by the time of the bad future.
The Bad Future results in the complete genocide of the mutant race and worldwide destruction. But think about how it all began, how history books would describe it. It all began with Richard Nixon. Sure, actually it was some low rank guy named Trask, but history books would remember who was in government back then and gave the green light to the Sentinel project.
The next train coming down the same tracks as the Sentinel transport is doomed.
RFK Stadium is visibly buckling from the strain when Magneto levitates it. In addition to however many people were killed when he dropped it around the White House (we see it land on a road-it's almost certain that some cars on it and buildings nearby were crushed), how many were killed or injured by lumps of concrete falling off the bottom en route?
If the time travel works as in the comics, the mind of 1970s Wolverine is inactive, replaced by that of his future self, and will return at the moment when the whole procedure is stopped. That means: whole 1970s Wolverine up to having sex, 1970s body with future mind during the action of the movie, 1970s Wolverine is himself again after it, until he is replaced again at the future year and saw the mansion again. Seems fine... but stop to think on it from 1970s Wolverine's view for a moment: one moment, he's in the morning after having sex with some girl, next moment, he's drowning in the Potomac river with lots of metal bars nailed in his body. What has happened here?
And a second one with this type of time travel. When it was done in the 1970s, the mind of 1970s Wolverine is inactive for a while, and returns when the whole thing ends. He gets out of the river, goes on with his life... and his mind is replaced again at some point in the future, and this time for good. Anything that Wolverine may have done in the interim years (things he may have learned, relations or projects he may have started, turning points in his life, etc) is now lost. As if losing his memory once was not enough, he must go through it a second time. First time he was hit with a simple amnesia, and he was a lonely man with no friends or relations to speak of. Second time, he's a professor and prominent member of the X-men, and he has his memories not lost, but irrevocably rewritten. To all his friends, it amounts to killing him and replacing with a similarly looking stranger.
Seeing as Wolverine was sleeping with the daughter of someone who appeared to be some sort of criminal, his first memory of the next morning being sunk at the bottom of a river might actually fall under fridge brilliance. Sleep with mob boss's daughter, sleep with the fishes.
The Sentinels' first step beyond "attack mutants" was "attack parents of mutants," which most likely started with killing women pregnant with mutant children, then killing the father to be sure.
This gets worse when you realize that the pregnant mothers and the fathers of their children probably wouldn't have had any way of knowing said child was a mutant, barring very extensive tests. Imagine a Sentinel just dropping out of the sky and murdering a random pregnant woman for reasons she herself obviously doesn't understand, followed by her boyfriend/husband being picked out of the crowd. This is probably where "mutant sympathisers" category comes into play... almost anybody who was expecting children and was even remotely concerned for their well-being would have to worry about potentially being a target.
In between the age of nine and twelve, Charles (and presumably everyone who knew him at the time) believed that he was mentally ill due to the voices in his head, and he would've most likely been diagnosed with schizophrenia. Psychiatric disorders carried a much greater stigma in the 1940's than they do now, and some of the treatments that were available at the time would be considered barbaric from a 21st century perspective. Xavier as a grown man resorts to isolation and substance abuse to numb the pain caused by his out-of-control telepathy, so imagine how much more difficult and terrifying his experience would've been as a helpless child. It's such a sensitive issue for him that he never informed Raven (who was his sister figure for 18 years), Erik (when they were best friends in 1962) or Hank (who was his sole companion for a decade) of his troubled past. While the X-Men Origins: Magneto script is not canon, Days of Future Past screenwriter Simon Kinberg nevertheless appears to have recycled the idea of Charles being treated like a schizophrenic patient when he was a kid, and these excerpts◊ give us a slightly better sense of how much it haunted him.
As all Cosmic Retcon stories, this one has a huge Protagonist-Centered Morality. The very idea of a world that ceases to be, to be replaced by a completely different one, is a huge horror if you stop to think about it for a moment. We have seen dead people who are now alive, and dead couples witch are reunited again, but things may be different elsewhere. The people who met and loved in the old timeline, may never met in the new one. The children of such unions, would simply cease to exist. Even more, a cosmic retcon does this to the whole universe, not just to Planet Earth, and the consequences for other worlds may be unpredictable.
Wolverine ends in the Weapon X program in the next film, X-Men: Apocalypse, which may seem contradictory with the ending of this film. Screenwriter Simon Kinberg explained that You Can't Fight Fate, that details may vary but Wolverine ended there because he was meant to end there. As Beast had said, time is immutable. Which means that the victory of this film is not a victory: someday, somehow, the Sentinels will raise anyway, and the world will be destroyed. Wolverine did not twarth destiny, he just delayed it.
Not necessarily, pretty much every incarnation of the X-Men establishes some sort of dark future. As Beast states in the '90s series if you destroy one of evil's forms it will likely just take a different form. It's pretty much canon that some form of dark future will happen in the near future, the trick is making it a dark future that can be endured.
Nightcrawler shows up in the next film as a teenager, some 20 years after both his comic book parents were members of the Brotherhood. In other words, Raven isn't just seeing autopsy reports of her friends, she's seeing one of her lover.