Continuity mistake: The woman has blood from the corpse upstairs dripping on her right hand. In the very next shot her right hand has no signs of blood, and she's shown wiping non-existent blood from her left hand. (00:16:14)
Other mistake: When Ben smashes the face of the ghoul trying to walk through the kitchen door, he comes back in and locks the door. But, when he drags the body of the ghoul he killed in the house out that same door and lighting it on fire, he runs back in, slams a small table against it but never re locks it. So until he boards it up, that door is left unlocked. That little table wouldn't stop anyone. (00:18:45 - 00:20:00)
Other mistake: Ben drags the body of the ghoul he killed in the house out the kitchen door. As he drags it out you can see he leaves it on the porch and lights it on fire, which would certainly set the wooden porch on fire and probably the rest of the house. But, once the flames are huge, you will see that the body has moved down onto the grass. But Ben never pushes it down off the porch. (00:19:45)
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)
Revealing mistake: As soon as Ben fires the first shot from the rifle you can plainly see it's a fake. Not so much from the look of it, but by the fact that there's no kick back whatsoever. The bullets you see him loading it with look big enough to give a pretty good blast. Even a .22 caliber would have more kick than what he's using. His rifle shoots like a BB gun. (00:45:35 - 01:28:30)
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.
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 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: 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.