Continuity: The front door changes in the interior view of Jackie's house a couple of times.

Revealing: Ken is killing Diane by stabbing her with the knife. You can see that Ken is only stabbing the floor next to her.

Continuity: When Maria is cleaning up the water on the floor, the rag is red in one shot and then blue in the next.

Continuity: When Sarah is walking down the blind alley to get to her car, the wall in the background changes from black to grey.

Continuity: When Duncan and Frank are murdered, their bodies are left on the floor of the foyer. In subsequent shots, the bodies have been removed and don't reappear until Jackie, Maria, and Diane head down to the basement.

Visible crew/equipment: As Janine re-enters the living room, a woman in a white T-shirt and jeans is visible in the room behind her.

Continuity: At the beginning of the film the teenagers are playing volleyball, Sarah has shorts on. Then she has on only a bikini bottom. Then she has shorts on. Then she has the shorts in her hands and picks them up. Later, Jackie and Diane are talking and in the background, Sarah has her shorts back on.

Continuity: Throughout the movie, the light in the foyer is always on, but through the window in the front door there's no light on.

Plot hole: When Sarah gets into her car she turns on her radio right away without turning on the car. Don't you need to start the car first in order to turn on the radio?

Continuity: As the pizza girl walks along the street, she walks past the same pick-up truck three times.

Revealing: Diane has a bloody wound on her left hip, before the killer actually cuts her with the drill.

Continuity: The amount of blood on the killer's shirt after Janine's death changes.