Continuity mistake: When Ben, Tom and Judy are trying to escape from the zombies in the truck, it is dark, but when the zombies are giving chase, dawn is breaking, and when the truck gets to the gas pump it is now dark once more. This is just one of a number of scenes in this film that change from darkness to daylight and vice-versa.
Factual error: In the 30th Anniversary version with new footage it is revealed that the first zombie we see (the one that kills Johnny) died in the electric chair. If that's the case, he should be bald with a large burn on his scalp, but he has a full head of hair. If he died in the electric chair then he shouldn't even have reanimated, as the method of electrocution kills by cooking the brain.
Continuity mistake: In the scene during which Mr. Cooper and Tom make their appearance, a large sweat stain mysteriously appears, disappears, and reappears on Toms shirt through the several shots that take place during a few minutes time.
Character mistake: After Ben tells his story about his first encounter with the ghouls, Barbara begins her story. She talks about the ghoul Johnny was joking about. She tells Ben that she wanted to apologize. She states, "I said good evening, and he grabbed me." If you go back to that original scene, you'll never hear her say "Good evening." (00:29:40)
Continuity mistake: Again, from the opening graveyard segment. As the first zombie approaches Johnny and Barbara, his position and distance from them changes inconsistently with the actual passage of time. Although he is incredibly slow moving, he manages to move about 30 yards in 4 seconds. He is about 25-30 yards away in one shot, and 4 seconds later he is coming up to Barbara and grabs her.
Continuity mistake: In the scene where the guy shoots the zombie through the boarded up window, the first time he shoots it through the left side. It then gets back up. When he shoots it through the right side and it gets back up, there is no bullet hole on the right.
Other mistake: A few minutes after Tom and Judy have been killed in the truck and their bodies burned by the fire, the zombies begin to eat some of the body parts. One of the zombies can be seen with a human hand that appears to be neatly severed and unaffected by the fire, surely the hand would have been so badly burned by the fire beyond all recognition.
Continuity mistake: In the scene where Ben is dragging the body out of the house to be burned, he is seen on the porch lighting the zombie on fire. The shot changes to show two zombies coming towards him, but when the shot goes back to Ben he is now off the porch about 5 to 7 feet with the corpse blazing in front of him.
Continuity mistake: Throughout the night scenes outside, patches of the terrain out in the middle of nowhere are mysteriously illuminated so we can see the zombies. Where is this light coming from? There are no street lights, no nearby houses, no car headlights, and the moon would not cast light in the shape of conveniently located spot light patterns where the zombies just happen to be walking or laying dead.
Revealing mistake: Early in the opening scene, Barbara and her brother Johnny are going to put flowers on their father's grave. As the two of them approach the gravesite, with Barbara leading the way around a low cut bush (centre screen), the camera angle changes and suddenly their positions in their walk have unrealistically changed. After Barbara says, "There it is," the camera angle changes and we now see Johnny walking behind the bush in a spot he had already walked (so he walks a small patch of lawn twice). Barbara instantaneously changes from walking full stride with her hands in her coat pocket to a momentary standing position with legs apart and the beginning of an initial step. Her hands are now no longer in her pockets but swinging at her side.