Continuity: In a scene where Logan pulls out the two horns from his stomach, the camera shows two holes on the singlet as part as his wounds. In the following scenes, the holes of the t-shirt have recovered (I know Logan has healing ability, but not his clothes).

Continuity: When Magneto lands the Golden Gate Bridge on the island, as it hits land it is still very light. When the Brotherhood start to walk toward the island, it cuts to a wide shot of them still walking on the bridge, and it's suddenly dark.

Trivia: Stan Lee makes a cameo appearance in the beginning of the movie when Jean is being recruited and showing off her powers. He is the man holding a hosepipe.

Continuity: As the scene where Angel is about to get the "cure" in the San Francisco skyscraper, you can see the reflection of San Francisco in the outside of the building - a huge hill with lots of buildings, and a large white tower at the very top. But when the camera switches to inside the building, looking outside, the view has suddenly changed to a view of the bay, and Alcatraz.

Factual error: Take a look at Google Earth - the section of the Golden Gate Bridge Magneto breaks off (tower to tower, with a bit of overhang, 0.9 miles at most, more like 0.85) is not long enough to reach Alcatraz - the two closest points are 0.96 miles apart, and that's the very end of a pier, which most likely couldn't support the weight of the bridge anyway.

Factual error: When Magneto has moved the Golden Gate Bridge, we see the President looking at a Satellite Image of Magneto's work. In this image, Alcatraz Island is bigger and closer to the shore than it is in real life.