Plot hole: When Andy turns into a werewolf, he kills both Amy and Detective Benbou. Later in the morgue, Amy tells him because of this that she is forced to become his "rotting sidekick." If this is completely true, then Detective Benbou should also be following Andy around but he isn't seen after Andy manages to escape from the morgue.
Plot hole: Near the end of the film, at the big party in the abandoned church, one of the main characters is tied to a crucifix. In the ensuing mayhem, we see the crucifix fall backward, with the guy on top of it, facing the ceiling. In the shot where the panicked partygoers are fleeing, we see this guy running out of the church, carrying the crucifix, which is still tied to his wrists. So, how did he get up? And if someone stopped to help him, which seems unlikely, given the general panic, wouldn't it have been easier to simply untie him? The alternative would have been to hoist the whole kit n' kaboodle upright, which, at the least, would have taken two people.