Continuity mistake: After parking the first truck in front of the mall doors, Roger jumps out and runs towards Peter's truck. Notice the zombie wearing the red and black striped rugby shirt. After Roger runs past him, he breaks zombie character and becomes concerned about his shirt being tucked in.
Continuity mistake: Near the end, Steven is in an elevator, and the zombie opens the doors and starts biting him. When he gets them all out of the elevator, blood comes out of his mouth and down the right side of his face. But later the elevator doors open and Steven is a zombie and the blood is on the left side of his face.
Continuity mistake: When they stop to refuel the helicopter at the abandoned gas station, a zombie approaches from under an airplane. In one shot, it is holding onto the wing support next to it - in the next shot, the zombie is standing in front of the support with its hand at its side.
Continuity mistake: When Peter has just killed the child zombies and another with a messed face is in the doorway, we see Steven outside aiming a rifle and it is cloudy, dreary weather. Peter dives out the way and lands by a window and we see that it is now pitch black, then Roger steps in and shoots the zombie from outside and it's only just overcast.
Continuity mistake: In the scene right after Francine is attacked by a Hare Krishna zombie, they are sitting, drinking and watching TV. When Roger is about to throw the bottle to Peter, he is sitting down, in the next shot after Peter gets the bottle, he is standing up and about to sit down.