The sound coming from the phone when Barbara (and later Ben) try to dial for help does not resemble any known telephone company signaling from the time, particularly anything from the kind of small-scale, electromechanical switching equipment that a farmhouse in rural Pennsylvania would be served by.
Ben contradicts himself all through the story he tells Barbara about the gasoline truck. First he says he had just gotten into a truck he found to listen to the radio when this happened. But then he says that when the gas truck came by it was all he could do to miss it - inferring he was driving. He also says that it was "screaming by" and that zombies were chasing it on foot and keeping up - but all the zombies we've seen can be out run by even Barbara. He also says that the truck was on fire during this chase and there were zombies hanging onto the truck yet we've seen that the only thing that scares zombies is fire.
Before Tom tries to convince Judy to leave, his left sleeve in cleanly torn, like someone has cut it cleanly away with scissors. In subsequent shots it turns to messily torn and then intact when he leaves for the trek to the gas pump.
When Tom, Judy, and Ben set out to gas up the truck, the original cemetery zombie menaces Ben, who sets his jacket on fire. However, when that zombie eventually breaks down the house's front door (with Johnny's help), his suit is in perfect, unburnt condition.
We see Ben pouring lighter fluid on a chair inside the house , planning to drag it outside and set it ablaze to ward off the zombies. In the very next scene he goes outside , and the chair is already on the front porch.
In the opening scene, Johnny tells Barbara that they have a "three-hour drive" ahead of them to return home to Pittsburgh. However, later in the film when the TV broadcast is listing local rescue stations, all of the town names given are located in the greater Pittsburgh area.
One of the lines assigned to the news reader is a quote from the chief of police in Camden, North Carolina. The city and county of Camden have a consolidated government with a sheriff and no police chief.
The first time we see the dead body at the top of the stairs, the face has been eaten away. Later when the body is being dragged away, the rug conveniently covers the face but for a split second we are able to see the face and it is clearly normal.
When Ben tackles the second zombie by the truck, he pins it to the ground right underneath him and starts beating it with a tire iron. You can see that to avoid actor injury, Ben is hammering the zombie at least 5 inches away from the zombie's head.
When Ben is nailing wooden boards to the door, small numbers can be seen on them. These were written on the backs of the boards so they could be removed and replaced in between shots, preserving continuity. Some numbers are visible because some of the boards were nailed on backwards.
When Ben creates a torch out of one of the table legs and is about to push the chair outside and light it in front of the zombies, he opens the door and for a split second you can see it is daylight outside, but it cuts back to nighttime in the next shot when he gets outside.
It becomes a plot point that the farmhouse's cellar only has one entrance, which leads into the living room area. But early in the film when Barbara approaches the farmhouse, an outdoor cellar entrance can be noticed.
After Tom and Judy get into the truck, there's a shot of Ben standing next to it, fending off the zombies with a torch. In that shot, the backs of two persons' heads are visible inside the truck - both male, and obviously neither Tom nor Judy.
Just after the car starts rolling down the road after Barbra releases the parking brake, she looks back at the zombie, then at the camera (possibly looking at Romero who was behind the camera) before looking back at the zombie.
Near the end of the film, there is a male and female zombie that are walking in an open field with a posse group right behind them that begins to shoot at them, but a few minutes later, the same exact male zombie is shot wandering near a couple of trees.
When the ghouls are eating the charred remains of Tom and Judy, burnt cuts along the edges of the bones can be seen indicating that the meat used in filming was cut with a high-speed saw frequently found in a butcher's shop.