When Bob returns to his apartment, having given Father Tom the
drugs Dianne brought him, it is clear that, as he walks the corridor, his apartment's door is open and light comes from inside. In the next shot, he opens the door to a dark apartment.
The goof item below may give away important plot points.
When Bob returns from burying Nadine, a puddle of water is visible behind Dianne and in front of Dianne, a board on the side of the road is clearly visible. However, these are not visible in the shot looking from behind Bob. They are again visible in the following shot from behind Dianne.
When Bob returns from his car in the motel parking lot, after having put Nadine's dead body in the trunk of his car, the door to his motel room is wide open. Cutting to the next scene however, you see Bob opening the door and entering the motel room.