Continuity mistake: When the bikers ride through the zombie infested town for the first time watch when Big Daddy is shot at. The windows behind him are shattered by the bullets but a few seconds later are fully intact. This may be hard to see as it is dark but they are back, easiest way to tell is by the reflection from across the street. (00:08:50)
Continuity mistake: When Kaufman sees Big Daddy, he shoots at him, particularly in his right shoulder. When Big Daddy turns to look at Riley at the end, the bullet holes are gone.
Continuity mistake: During the scene at the club where the zombies are used as entertainment, someone sprays the checkered shirt zombie with red paint around his mouth. However, in the next shot from a distance, the spray paint is gone.
Answer: Riley feels that they have just the right to be there as the living do. Besides, those zombies survived all the missles and are coming to the city while Riley and the gang are leaving. So why waste the ammunition?
Jason Riley