Plot hole: In the scene with the brothers group, the guys don't believe that Fred is Santa Claus's brother (because they don't believe in Santa). But why don't they believe in Santa? Santa leaves gifts for kids on Christmas. If they don't believe in Santa then where do they think the presents came from?
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.