The first US studio film to contain a scene depicting bestiality.
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.
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.
Alice's Restaurant was filming at the same time in the summer of 1968 in Great Barrington, Massachusetts. Actors M. Emmet Walsh, Graham Jarvis and Ray Brock were cast in both movies.