There was a bit of controversy surrounding this film upon its release when it was leaked that director Michael Winner used real human oddities for the Dead rising up from hell scene at the film's conclusion.
Cameo: [Richard Dreyfuss] Man talking to girl in red sweater as Cristina Raines and Deborah Raffin are walking on the sidewalk.
Universal had hoped to sign on 'Don Siegel (I)' as director, but Siegel ultimately bowed out due to his discomfort with this particular movie genre.
Kate Jackson was asked to play Alison Parker, but turned down the part.
The book on Milton's poems that Professor Ruzinsky hands to Lerman was edited by Maurice Kelley (1903-1996), an actual Milton authority.