Revealing mistake: In the scene in the laboratory under the mansion, when Wolverine confronts Jean about Cyclops, there is a close up shot of Wolverine's hand holding Cyclops' glasses. In this shot there is a small cut visible on Wolverine's hand - his healing power should not allow this.
Revealing mistake: When the truck leaps off the ferry, the underside is seen, exposing the still-flaming 'roll cannon' opening in the rear floorboard. This cannon is what caused the rear of the truck to rise, sending the truck flipping through the air. (01:52:30)
Revealing mistake: Just before the end credits, as Superman is flying past Metropolis and into space, watch the car headlights in the background. The background shot is blatantly sped-up by a large amount, as all of the cars appear to be travelling at huge speeds, even in a traffic jam.
Revealing mistake: When one twin (presumably Alfred) is removing the other twin's fingers, "Alfred's" upper arm passes through his twin's head as "Alfred" reaches for the hammer. [Fixed on DVD.]
Revealing mistake: When the woman is taking the pictures at the start, the camera lens has got the cover over it. (00:07:00)
Revealing mistake: Anytime we see the back of someone's head while they are talking, their mouths aren't moving.
Revealing mistake: Near the end of the movie, when Starla is flung about by Grant, in some shots it is obvious that Starla is replaced with a stunt double, as there is a noticeable hair change in some of these shots.
Revealing mistake: You can see the charges to break the glass armor at the chest of the first guard when Violet kicks down in the vault. (00:16:30)
Revealing mistake: The infant baby was computer animated in every scene in which the face appeared. Even the feet were obviously touched up by computer in the hallway scene. The lighting isn't quite right, the skin texture isn't quite right, and the child's face is just too animated.
Revealing mistake: When the American man throws a square concrete tile at the monster it reacts (moves its foot in pain) before the tile actually makes contact. (00:16:11)
Revealing mistake: They let us see the stunt double's face for the girl Steven Seagal is fighting in the ending Cathedral scene, and she looks nothing like the actress.