Factual error: Throughout the series, there are scenes of decapitated heads speaking with audible voices, in spite of the fact that they have no diaphragms, lungs or larynxes. Even if a decapitated head was somehow fully animate, it still couldn't utter a sound.
Factual error: In a scene when the group is supposed to be near the east coast a Banner furnace and fuel truck explode, the problem is, Banner Fuel is only in Spokane, WA, on the west coast. Spokane is where the show is filmed.