Factual error: When Tom shocks Angela with a stun gun, she gets knocked out. That's impossible. Stun guns don't knock you out. Stun guns don't cause unconsciousness.
Plot hole: Jim leaves to attend his family Christmas as evident by his dialogue in the opening scene, and evidently Carl is supposed to be at home to his family in the morning as well, but both are killed by Thomas. When the movie ends with Angela entering the city, it is early morning just before sunrise. Jim and Carl's families would have noted that they were not home on time, and therefore would have had someone searching for them. This makes it implausible that Angela's situation would not have been discovered.
