Corrected entry: When the X-Men are running out of the dam, Ororo and Kurt are holding Professor X up. Kurt is on his left, and Ororo is on his right. In the next shot, they've switched spots. They could have stopped and swapped places, but that would have slowed everyone down considerably, so they probably didn't.
Corrected entry: When Cyclops goes to check if Jean Grey is alright after recovering from Stryker's mind control, we see him walk around and grab Jean before quickly assuring her that he is fine. Trouble is, we only see him walking to find her. Given their serious situation and his love for Jean, he would definitely have being moving much faster (running even).
Corrected entry: When Xavier is being brainwashed into killing all the humans via Cerebro, there's a fly-through of the Cerebro map and all of the screaming people. Earlier you could see the outlines of the continents because of the people, but in this fly-through, Japan, Great Britain and Ireland are missing, even though they are not uninhabited.
Corrected entry: Obviously Jean has new powers is X2 and Cylops mentions Liberty Island to her in the museum scene. Now watching the Liberty Island scene again in X-Men 1 when Wolverine is trying to slice up Magneto's machine, you'll notice two things. 1. There is some sort of firey substance around Wolverine's hand. Possibly Jean helping him and not realising? 2. When the machine has been destroyed, Jean looks shocked/surprised at something. Possibly the display of power, or maybe the radiation having an effect on her?
Corrected entry: In the scene where Nightcrawler tries to kill the President, the Agent who shoots him is lying on the floor right behind him. This means that Nightcrawler was shot in the back of the arm. But when Storm and Jean are cleaning his wound in the church, the bullet hole is more in the center of his arm.
Corrected entry: In the beginning of the movie in the museum scene when everyone other than the mutants are stopped and frozen in time, look closely and you will see a young girl who slightly moves positions even though she is supposed to be completely still.
Corrected entry: When Wolverine is shot in the head, his Adamantium skull blocks the bullet, which means he only has a simple flesh wound. Based on this and on how fast he heals from far worse injuries, it shouldn't have taken him so long to heal, and it shouldn't have knocked him out in the first place.
Corrected entry: Logan takes a bullet to the head which knocks him out. The scene develops where the wound begins to heal (finally) and the slug pops out. Lead is a soft metal and adamantium is the hardest and indestructible. How did the slug lodge? There's not enough flesh in that spot to hold it in place.
Corrected entry: In the Oval Office at the end of the film, Professor Xavier uses his telepathy to freeze all the people in the room. When the shot switches to a front view of the X-Men, watch the frozen people in the background closely. They are all quite good at being perfectly still, except for a blonde woman who is blinking rapidly and breathing heavily.
Corrected entry: In the scene where the X-men's jet had just gotten hit by the missile, and Rogue is thrown from the plane, Nightcrawler warps out and grabs her, then warps back into the plane. Doesn't he later say in front of Cerebro that he can't warp to places he can't see? I don't think he possibly could have seen into the plane from below and behind it.
Corrected entry: When Stryker stands in the Oval Office to talk about his plan for invading Xavier's school, you can see an 'X' behind him in the decor, just above the door.
Corrected entry: Nightcrawler is set up all through the movie as being a Catholic, using a rosary and so on, yet when he recites the 23rd Psalm, he recites the Protestant version and not the Catholic one.