Continuity mistake: In the scene where Ray goes to "protect" Kelly, shots are fired. If you compare the events of the entry, smashed glass, first 2 shots, last shot, you will notice there is an obvious difference in time between events in the showing from outside the house to inside the house.
Continuity mistake: At the very end when the movie shows what really happened when Kevin Bacon shot Denise Richards, he wraps a handkerchief around his hand and punches a dinner plate sized hole in the gun case to pull a gun out. When he turns around and the camera angle changes, the gun case's glass is almost entirely broken out.
Continuity mistake: When Ray Duquette and his partner are interviewing Susie's Grandmother about her disappearance, Walter is playing with the false teeth in the background. In one shot Walter is holding an almost unsmoked cigar and when the switch back to him and he puts it in his mouth, the cigar has shrunk to about two inches.
Continuity mistake: In the scene where Kelly Lanier Van Ryan is giving her testimony of the rape for a video recording, the microphone is on the right of the screen. In the next scene, where the cops are watching the videotape of the testimony, it's on the left.