Continuity: In the scene where Walter is being rescued from the room he was trapped in through the hole in the wall, we see the outside of the hole and Walter's body is outside except for his legs, and we see the hands trying to pull him back. In the next shot inside the room, Walter is again inside except for his head and arms. It repeats several times.

Continuity: Susan and Lisa are standing perfectly still for a long time awaiting the transformation of the possessed girl, yet Lisa's hair goes from being behind her back to over her front then back again when the possessed girl "wakes" up.

Revealing: Just before Walter throws Lisa through the window, you can tell that Lisa is a stuntman wearing a wig.