During the initial zombie hunt in the field, a number of zombies are destroyed, moments later they are seen walking. Most notably is a tall zombie wearing a blue T-shirt, who is shot in the head and killed, then seen attacking the helicopter pilot where its shot in the head for a second time.
When Deputy Hughes puts the "dead" zombie in the front seat of his car, he's behind the steering wheel, alone. When Hughes shoves the car off and the other cars go after it, however, there's another head visible in the passenger's side, and this is the body the zombies go after.
When they are ready to burn the zombies, some asks, "It's that all?" Another person says, "yes," even though they are walking around bodies scared around the ground. However, when the sheriff lights the fire, the ground is cleared of zombies.
When Hughes fights the zombie by his car (just before blowing it up), he throws the zombie to the ground and shoots him multiple times. The slide on the semi-automatic handgun he is shooting locks to the rear, indicating it is empty yet he rolls onto the hood of his car and fires at several more zombies in the field.
When Hughes shoots at the car, he is using a Thompson Contender scoped handgun. The scope has an extended eye-relief--meaning to get a proper sight picture, it should be held at arms length. He holds it right up to his eye, where it would not work properly. Additionally, the recoil of this rifle-caliber handgun would have cause the scope to hit him in the forehead.