After Kent kills Vance in the kitchen, a dish rack is positioned toward the edge of the sink, but when Kent washes the bloody doll in the sink, the dish rack has vanished. (In this case, it has been removed to make room for the camera.)
When Kent and Joey enter the storeroom, it's pitch black, but much more illuminated in subsequent shots.
When the sex toy is thrown to Kent, he drops it and catches for the door frame. But by the next shot, he's not holding it.
When Vance carries the presumably unconscious or dead Debra, she clearly grips his arm or shoulder to keep herself from sliding to the floor when she is laid down.
When the police arrive at the scene, Mrs. Andrews can be seen breathing while being dead.
During the scene where Vance confronts Kent in the kitchen before he gets stabbed by him, a blue-shirted crew member (perhaps a camera assistant) momentarily appears and then moves out of frame. In addition to that, the shadow of the cameraman can be seen passing over the wall beside Vance and onto the wooden cupboard.
In the scene where we first see Laurie Ballard tied up in the bed and Vance enters the room, the shadow of a boom mic is clearly visible on the wall behind them.
When the killer first puts on the ski mask, he does so improperly, allowing him to see through only one of the two eye holes.
The car accident victim's arm drops limp on the hospital trolley, indicating death - despite the fact that the preceding shot shows paramedics covering her head at the scene of the crime, indicating she was already dead.