Continuity mistake: At the start of the movie Dylan Walsh cuts himself shaving and patches it with a piece of tissue, on the side of his jaw. Moments later as he's walking through the house the cut has moved to the corner of his mouth. (00:01:40 - 00:03:35)
Factual error: In the beginning of the movie after the 1st murders, when the detective is talking, he states that Grady's/David's car was bought with cash, and the purchase is untraceable because no ID is required, this is not true. A valid picture ID or drivers license is required in order to register the vehicle. Whether it is a fake ID or not, a person has to come up with some sort of ID in order to register a car. Otherwise people would just keep re-registering their vehicles under false names instead of paying parking tickets.
