Revealing mistake: After Toad spits his slime at Jean Grey he falls to the floor. You can see the tether that was holding him in mid air. (01:13:55)
Revealing mistake: While the guys are going for their physicals, there's a scene in which blood is drawn and you can clearly see the tube connected to the end of the syringe pumping fake blood into the container.
Revealing mistake: Many times throughout the movie, people are shot and they bleed, but their clothes don't have holes from where the bullets hit them. The most noticeable examples are when the teacher is shot at the end, and when the big gun fight between the girls breaks out in the lighthouse.
Revealing mistake: When Jonny is running away from Terl in the mall at the start of the film, he goes through several panes of glass, smashing through them. One of them breaks up before he hits it.
Revealing mistake: In the parking garage shoot out Arnold shoots the leg off a bad guy. While the bad guy is writhing in pain on the ground you can see his leg tucked back. (00:59:50)
Revealing mistake: When the bleached dead girl is lying on the table, you can see her breathing. (00:13:45)
Revealing mistake: Right at the beginning of the film when the crew walk down the tunnel from the shuttle to the space station, one on the left of screen bumps into the massive metal airlock door. It wobbles.
Revealing mistake: In the fight scene between Riddick and Johns, there is a wide shot of them both fighting over Johns' shotgun. In this shot it is apparent that it is not Vin Diesel in the shot but in fact a stunt double. (01:17:35)
Revealing mistake: Sebastian Caine wears a latex mask and latex gloves in order to appear near-human. The mask he wears is fairly long, and covers his neck, and the tops of his shoulders and collarbone. However, there is a scene in which Linda and Matt are helping a nauseous Sebastian reach the toilet, where he vomits (invisible fluid) into it. In this scene, when Sebastian breaks free from them and runs to the toilet, we can see that his arms and chest are also visible, skin-colored. The mask he wears only reaches the very base of his neck, so it is possible that the actor playing the invisible man did not realize that the tops of his arms and chest were visible. (00:49:20)