David Hess was the first choice for Alex because he played a similar villain in The Last House on the Left (1972), which was a highly successful low-budget thriller. The makers of this film wanted Hess involved so much that they gave him half the rights to the film.
Because Wes Craven's The Last House on the Left (1972) had been such a success, this film, which is similar in violent content and also stars Hess, was given the slightly similar title "The House on the Edge of the Park". It was one of many violent thrillers to be given a "House" title in attempt to ride the success of Craven's earlier film.
In 2006 the BBFC conducted a research study on people's responses to films that included scenes of sexual violence. This film was selected to be examined in the study because of its notorious reputation with the UK censors.
Alex's first rape victim is in fact David Hess' wife, acting under the name Karoline Mardeck. (There is an interview with her on the Region 1 Shriek Show DVD.)