David Mucci, who played troublemaker Lou, had a serious medical condition. He was forced to be immobilized underneath the stage for the scene in which Lou is decapitated. He was terrified that something would happen while he was trapped there so director Paul Lynch held his hand for the duration of the scene to assure him everything would be all right.
In one of several scenes removed from the theatrical version of the movie, Principal Hammond takes his wife to visit Dr. Fairchild after a visit to Robin's resting place at the cemetery. As Vivian is seated in the office and the men talk privately in the hallway, it is revealed that Robin and Alex are twins.
According to director Paul Lynch in the documentary "Going to Pieces: The Rise and Fall of the Slasher Film", he was having difficulty securing financing until Jamie Lee Curtis signed on. Once the film was shot, Paramount expressed interest in distributing the movie. However, they only wanted to open it in 300 theaters whereas Avco Embassy Pictures offered to release it in 1200 theaters. Avco Embassy released Prom Night as a result. That same year, Paramount released another independent slasher film, Friday the 13th (1980).