All the extras who portrayed zombies in the climax received for their services a cap that said "I Played A Zombie In 'Day of the Dead'", a copy of the newspaper from the beginning of the film (the one that says THE DEAD WALK!), and one dollar.
On the special edition DVD, director George A. Romero claims this is his favorite film out of the original "dead trilogy".
According to Lori Cardille, the first attempt to shoot the beginning dream scene where the zombie arms suddenly spring out of the wall and attack her resulted in the faux wall and many of the actors behind it toppling over on her. The wall ended up needing to be completely rebuilt, this time much more stable.
The original script, for which George A. Romero couldn't get budget, involved the scientists living above ground in a fortress protected by electrified fences and the military living safely underground. It also involved a small army of trained zombies, and the conclusion to the trilogy more brutal than the released version. This later became the basis of Tierra de los muertos (2005)
The underground facility was not on a soundstage. It was shot in the Wampum mine, a former limestone mine near Pittsburgh, that was being used for an underground storage facility. The 2,500,000 square foot mine is now operated as the Gateway Commerce Center and referred to as a "subsurface storage facility".
Akram Midani: The former Dean of Fine Arts in Carnegie Mellon appears as a Fisherman Zombie pursuing Steel through the Mines. (You can see his wife Watfa Midani right next to him as another Zombie.)
Taso N. Stavrakis: In 2 roles: Appears as a Cave Zombie who gets bashed on the head with wood by Sarah. Referred to as Knock-On-Wood Zombie. He also appears as a Biker Zombie as the Zombie battle begins.
George A. Romero: [clown] The first film in Romero's "Dead" series to have a clown zombie, as also seen in Tierra de los muertos (2005) and El diario de los muertos (2007).