Visible crew/equipment: In the scene in which Zed & his fellow exterminators chase down several brutals on the beach, tire tracks from the camera vehicle can be seen briefly imprinted in the wet sand.
Other mistake: The extras in the shot where Zed pulls the cart through the courtyard of apathetic are the same extras used in the shot where he pulls into a barn. Even if they could move, that's awfully quick. These people are supposed to be zombies. (00:38:00)
Revealing mistake: In the very early scene in which Zed points his revolver directly toward the viewing audience and shoots, it's visible that there is no ammunition in the gun's chambers.