Continuity mistake: When Larry is taken home after being bitten by the werewolf, the door opens and Larry is seen staggering in. In the next shot, the door is seen opening again.
Visible crew/equipment: After the moving candle/ghost incident involving Ferdie and Camille, and before Moose Matson's money is discovered, Chuck and the doctor come running in, and they all start yelling and talking, there is a person (probably a crew member) briefly visible in the round window in the door in the background.