- Storm using a summoned blizzard to force Jason to release his illusion's hold on Xavier makes a lot more sense if you see The Cameo of a younger Jason frozen in cryogenic stasis in Origins: Wolverine.
- If you read The Once and Future King after watching the X-Men movies, you will find dozens of ways that it is relevant, some of which, based on the film commentary, the directors weren't even thinking of. For example:
- Obviously, the ending of the Arthurian mythos is about good friends being divided by differing principles and priorities and fighting each other.
- There's a lot of discussion (by Merlin) of the need to forget and move on from past, and even ongoing, oppression and injustice, on the basis that starting a war is inherently wrong even if you've got a lot of justification for doing so.
- Arthur, early in his kingship, is described as a cheerful and idealistic young man who more or less regards suffering as non-existent due to not having truly experienced any. Now watch X-Men: First Class and look at Xavier...
- It takes Professor X so much longer to find all the mutants, who are a much smaller portion of the population, then it did for him to find all the humans. The reason why had already been provided earlier in the film. Xavier had trouble locking on to Nightcrawler because he's a teleporter and his mind is slippery to a psychic. It may suggest that other mutants are mildly shielded against telepaths, and it makes sense that Professor X has a much harder time finding all of the mutants than humans who have no shielding against him.
- Xavier mentions that Nightcrawler is hard to track because of his teleportation powers. With some better wording and adjustment, this could explain why Charles couldn't just command Azazel to help him at the end of First Class.
- Storm is talking about Neanderthals and Cro-Magnon men. At first it seems unimportant, but then I realize it can be applied to humans and mutants: Magneto believes mutants will replace humans (theory that Cro-Magnons replaced Neanderthals), while the X-Men believe that co-existance is possible (theory that modern humans are the result of Neanderthals mating with the Cro-Magnon)
- In the finale of X-Men 2, just before Storm and Nightcrawler rescue Xavier from Jason's mind-control powers, how come Storm immediately knew that the 'little girl' wasn't a little girl at all, while Nightcrawler was totally convinced? Jason was a student at Xavier's school in the past, and it's possible that Storm remembers him, and his distinctive heterochromatic eyes.
- Logan tells Iceman's parents that he teaches Art. This is likely to tell a half-truth without making them concerned about their son being taught martial arts at what they believe is a regular boarding school.
Fridge / X2: X-Men United