Character mistake: John shot at the "werewolf" but wasn't successful in hitting it. Instead of pursuing the werewolf, who he supposedly was determined to catch, he let it run away. Alcoholic or not, a sheriff's deputy should have done everything possible to try to capture the creature that was terrorizing the small town. By not even attempting to follow the werewolf, John missed the one opportunity he - or anyone else - had thus far to potentially put an end to the senseless and tragic murders of young ladies. (00:55:35)
Suggested correction: Dude's daughter was attacked and bleeding from the head, of course he didn't pursue it.
Suggested correction: He didn't go after the wolf because his daughter was hurt, and his (albeit misguided) parental instincts took over. It's not at all a character mistake for him to prioritize making sure his daughter is all right over chasing a perp. Most parents would probably do the same thing.
Character mistake: If the murders were happening during full moons in December and Jenna had not yet started the college classes she was going to take in January, it doesn't make sense that John told Paul Carnury that he was returning the items he confiscated "a few months ago." The items being returned to several of the residents, including Paul, were related to the murder investigations which were more recent.
