To date the film has never been submitted for a UK certificate. Its British release was without a certificate at the ICA Cinema in the Mall, London, showing at weekends from 17 June 1972. It has not been commercially released in the UK since, and has not to date been shown on British television.
The first US studio film to contain a scene depicting bestiality.
Some of the hospital inmates were played by real patients on leave from the Austen-Riggs Psychiatric Institute.
The train station shown in the movie is the Villanova University stop on Amtrak's Paoli Local line. Other scenes are shot in the area also.
Stacy Keach and Harris Yulin teamed up again in the revisionist 1971 Western 'Doc' (1971), with Keach as Doc Holliday and Yulin as Wyatt Earp.