Continuity mistake: When Bucum is in the trailer at the beginning of the film, and the woman starts shooting at him with a shotgun, he runs and dives through a window. Before he dived through the window he had his pistol drawn. But when he's flying through the window, you can see it in the holster on his leg.
Continuity mistake: In the scene when Bennie comes back to Banks, she asks him about the papers he's been reading when she sat down opposite him. She then tries to take the papers, but Banks slams his fork into them. In the next shot you can see Banks holding the fork next to his face then, in the next, he presses the fork against the papers again.
Continuity mistake: When the security guard steals the hitman's bag, he tosses it into his car and takes off. But when the interior shot of the bag being thrown in is shown, it is a leather seat and the floormat has a Thunderbird logo. The security guard was driving a lime green Yugo, not a T-Bird.
Factual error: At the end of his first session with the lady doctor, the serial killer touches a guard and makes him crazy. The guard goes into an office, grabs a shotgun, sticks it right under his chin and pulls the trigger. The gun is pointed straight up, but the blood splatters straight back onto the wall behind him, not up into the air.
Continuity mistake: When Jack Friar is with Tyrone and Erin in the traffic jam on the freeway, he puts his red flashing light on top of his car and takes a detour on a dirt path. Shortly after, a motorcycle policeman pulls up beside him and Jack flashes his badge. The next shot is a view of the car from far away and the red light is no longer on the top of the car.
Continuity mistake: In the scene where Carla and Darl are talking in front of her house, she closes the back door to her car. In the next shot it is open and closed again in the next one.
Continuity mistake: When Dahmer gets upset and tries to tackle the wrestler, he is thrown on his back and grabs the guys shirt. The shots after that switch between holding the shirt and not holding the shirt.
Continuity mistake: In the scene where Trish gets shot in the head by Vic, she falls backwards onto a bed and lands inbetween two duffel bags. When Jack looks over to her, the camera shows her again, and the bag that was at her right is no longer there.
Plot hole: Throughout the movie, the flies are vulnerable to light (direct sunlight and even lightbulbs) to the point of incinerating in a split second. Except... they are not; in several sequences they fly to and from bodies and without even taking a direct path (look at all the action happening in front of the house, by the cars, in broad daylight).