Josh's magic sweater. Josh did not have a sweater when the vampires abducted him, however when Josh is talking to Douglas after the vampires have left he is wearing a sweater. The next shot, no sweater. Then the sweater reappears again. Then it disappears.
The padlock on the cage that Josh is being held in appears unlocked at 23 minutes and 16 seconds, although it is supposed to be locked.