Originally, one idea for the script called for Harry Cooper to die from the gunshot wound received from Ben before his daughter became a zombie, which would have resulted in Helen coming down the stairs to find him eating their daughter, rather than the daughter eating him. It was decided that this would probably be far too disturbing and graphic and was changed back to the idea of the daughter becoming a zombie first.
Readers Digest tried to warn people away from watching the film in 1968 by claiming if it's ever watched, it will inspire cannibalism.
Screenwriter John A. Russo appears as the ghoul who gets his forehead smashed by Ben with a tire iron. He also allowed himself to be set on fire for real when nobody else wanted to do the stunt.
Some of the groans made by S. William Hinzman when he's wrestling with Russell Streiner in the cemetery are authentic. During the struggle, Streiner accidentally kneed Hinzman in the groin.
The body upstairs in the house was made by director George A. Romero, who used ping-pong balls for the eyes.
The character of Ben was originally supposed to be a crude but resourceful truck driver, with no specification to race. After Duane Jones, in real-life a self-serious, erudite academic, auditioned for the part, director and co-writer George A. Romero re-wrote the part to fit his performance.
The character of Ben was originally written as an angry person. When Duane Jones was given the role, he expressed concern that the character be rewritten to remove some of the anger - such as the scene where Ben hits Barbara - afraid of how it would be widely perceived in the United States at the time to see a black man acting in this way. The nation was still plagued with high racial tensions during the late sixties; the film was released to theaters shortly after the assassination of Martin Luther King. Nonetheless, George A. Romero and most of the rest of the predominantly white crew decided against it, thinking they were being "hip" by not changing it. Years later, Romero lamented that he had not taken Jones' concerns more into consideration, and thought that he was probably correct. He's expressed that he wishes he could speak with the late Jones again, asking him how he felt about the film's legendary status, and believes Jones would just say "Who knew?" and laugh.
The Chevy truck seen in the new footage is not the same one seen in the original footage. The filmmakers for the new footage were fortunate enough to find a truck owned by a local resident that bore a near-perfect resemblance to the original truck. The owner was kind enough to let them borrow his truck for the film.
The Cooper family are partly played by a real family. Karl Hardman (husband Harry Cooper) is the real life father of Kyra Schon (daughter Karen Cooper). However contrary to what is elsewhere reported (and was previously reported here on IMDb) Marilyn Eastman (wife Helen Cooper is not in any way related to either Karl or Kyra.
The ending originally had Ben surviving but it was changed to something far more shocking. Having the hero die after all.
The Evans City Cemetery was the cemetery used in the original version of the film, but it could not be used for the 30th anniversary edition. Before filming the new footage, a tornado had torn through the Evans City Cemetery, and ironically, it unearthed several graves.
The film was shot in black & white because there wasn't enough money to transfer it into color.
The film's first scene, the initial cemetery attack on Barbara and Johnny, was the last filmed, in November 1967. The actors had to hold their breath to avoid visible condensation in the frosty autumn air.
The film's world premiere was at the Fulton Theatre in Pittsburgh, Pennsylvania, on 1 October 1968 (At 8PM, admission by invitation only). The film was met with a standing ovation.
The filmmakers were accused of being "Satanically-inspired" by Christian fundamentalist groups for their portrayal of the undead feeding on flesh and of the Coopers' zombie child (Kyra Schon) attacking her mother (Marilyn Eastman).
The first movie filmed in Pittsburgh.
The gas pump was not bolted to the ground when the actress who played Barbra, Judith O'Dea, runs into it at the start of the film. She did it with so much force she almost tipped it over on the cameraman.
The house used for this film was loaned to the filmmakers by the owner, who planned to demolish it anyway, thereby ensuring that they could do whatever they wanted to the house.
The main house did not have a true basement but a dirt potter's cellar, and thus had no long staircase leading down to it. Because of this, the basement scenes were filmed in the editing studio's cellar.
The matricide scene was accomplished by having Kyra Schon stab repeatedly into a off-screen pillow with a trowel while a member of the effects crew threw chocolate syrup (used as fake blood for a black-and-white film) onto the wall. These scenes were looped with scenes of Marilyn Eastman screaming. The trowel used in the scene was purchased online years later and is now in a private collection.