Revealing mistake: In the end when Mulder is reading the paper in the park. The paper is clearly a prop. Only the frontpage is real - when he puts the paper away you can see that the rest of the paper consists of blank pages. (01:45:45)
Revealing mistake: When they are all in the camper van Tiffany gives Chucky a biscuit then walks away from him, from the way she gave him the plate, they would have all fallen off. (01:07:35)
Revealing mistake: When Montoya uses a spear to toss the vampire woman from the prison door into the sunlit street, it is an obvious dummy that has been used. First you see the woman stumble out, and the first flames shoot out of her, then the angle changes to a close-up of her as she is engulfed in fire. In the close-up, she has become bigger and rounder, and does not move.
Revealing mistake: When Charlie turns and sees Michael after futzing with the garbage disposal, it's obvious that Michael's mask is a (rather poor) CGI creation. It looks very cartoonish and unlike the way it looks in the rest of the film. The scene was shot early in production with an original mask that eventually was tossed out for the final design when producers thought it didn't quite look right. Because Michael was in a medium-closeup shot and they didn't have time to reshoot the scene, they opted to (somewhat obviously) digitally replace the mask.
Revealing mistake: When Karen and Whistler start to fire at Frost's men, after they discovered Blade's hideout, Whistler shoots a black guy who has a large bump under his shirt, quite obviously the squib. (01:11:00)
Revealing mistake: At the beginning, the dead policeman can be seen rolling himself with his arms. (00:06:45)
Revealing mistake: Near the end (DVD), when Sadako comes out of the TV, you can see where her finger extensions have been placed (you can see the join between her real finger and the fake one). (01:22:50)
Suggested correction: She's not wearing finger extensions. There are small prosthetics to make it look like her fingernails are missing, but her fingers are normal length.
Revealing mistake: When Natalie is in the old building and she is looking around, she opens the door and Parker's dead body falls out onto the floor. When it cuts to a close up of his body, you can clearly see the side of his neck pulsating although he is dead. (01:19:50)
Revealing mistake: After Beloved's ghost throws the dog against the wall its eyeball hangs out. In some shots the dog's real eye is visible too. (00:01:30)
Revealing mistake: When one of the bad guys is being dragged around by the monsters and thrown against pipes and walls and such, in wide shots you can see there is no monster really pulling him, and from the stiffness and position of his body, he is likely on some sort of device to swing him around.
Revealing mistake: As a homage to the original; when Norman carries Marion's dead body, wrapped in the shower curtain to the car, you can see her bra strap through the curtain.
Revealing mistake: When the two women first enter the sheriff's station there is a dead deputy on the floor with a Beretta 92 in his right hand. There are two mistakes in this scene. First, he supposedly died firing the gun, but the hammer is decocked which has to be done manually. Second, one of the shots shows three spent cartridges on the ground. The shells have brass crimping opened on the front. Real shells have no need for a crimp because of the lead bullet. It is obvious that they fired three blanks out of the gun and used those shells in the shot.