Layne drives two different VW Beetles in the movie. One car seen later in film has the stock front hood and fenders, while another seen early on has a modified "dune buggy" front end, with the headlights moved to the center. The rear rims on Layne's VW changes style from scene to scene. In some scenes, they are of a five-spoke style (which match the front rims) while in others the rims change to another style.
In the opening of the movie, the younger brother throws his sister's doll off a bridge. We see a completely different doll hit the water below.
When Layne and Samson are driving in the car together at night, the shadow of the rear-view mirror is visible on Samson's face. In the long shots, the shadow appears to have a cross hanging from it, but on the close-ups of Samson's face, there is no cross.
At the beginning of the film, during the first close-up of Jamie's face, her tongue can be seen to move slightly.
When Layne kicks Matt and Clarissa out of his car, he does so in front of a gas station. The lights are on, so the station appears to be open, but as they walk past, you can see that the station has no gas pumps.
Jamie has been murdered and her body is lying out in the open for several days, but there is no indication that her family or anyone else has reported her missing, which would have made Samson, her boyfriend, an immediate suspect.
Although Jamie's body lies out in the open for several days in the film, there are no signs of decomposition.
When Tim checks the bullets in the gun, all three shells are spent.
When Layne makes the phone call to Feck from the phone booth (right as the police burst in on Feck), the reflection of a crewmember in a light colored shirt can be seen moving in the glass of the phone booth.
When the detective is questioning Matt in his office, the boom mic is reflected on a glass case behind the detective's desk.