Director Jorge Grau purposely cast an actress known for having a flat chest in the role of the nurse so that a fake chest piece could be applied that the zombies could tear into for her death scene.
The film has a grand total of 16 alternative titles from its various international releases.
The film's strange music score is partially made of moaning and breathing noises. It was director Jorge Grau who made these eerie sounds, as well as those for the zombies.
The film's bizarre alternative title, "Don't Open the Window", inspired Edgar Wright to make his mock-trailer, "Don't", for the film Grindhouse (2007).
The cemetery scenes in the film were shot at the historical English graveyard where Robin Hood's Little John is said to have been laid to rest. The production experienced trouble though when tourists arrived to see the crew (and their garbage) hanging around the cemetery. Complaints were made and the film crew was forced to wrap shots in the cemetery in 24 hours.