Continuity mistake: When the bodyguard finds Gale eavesdropping on Dewey and Jennifer, they soon confront each other and Tom is sitting in a chair with his left hand on the arm rest. In the next shot Tom is smoking a half finished cigarette with his left hand, but he had no time to change the hand with the cigarette in it between shots. (00:40:00)
Continuity mistake: The knife that was thrown at Dewey left the killers hand with blood all over the blade, but was perfectly clean when the butt of it hit his head to knock him out at the top of the stairs. (01:26:55)
Continuity mistake: At the part where Sidney is on the set of her house and the killer is chasing her up the stairs, she runs right by the plants, but in the next take she is right next to the plants just about to throw one. (01:05:25)
Other mistake: When Sidney is on the set with her mother's covered body, it rises up and reaches for her, speaking in her mom's voice. Sidney calls out for Dewey before climbing out of the window. However, when she's grabbed, she yells out her own name: Sidney.
Revealing mistake: When the house blows up and Dewey, Gale and Jennifer jump off the balcony, we find that Gale is near the car, the killer jumps up behind her. Dewy takes a shot at him with a gun and it is obvious that the killer awkwardly slams himself against the car window, rather than being caused by the impact of the bullet.