From The Grindhouse Cinema Database
- Cameo: [Buck Henry] Film's writer is the strait-jacketed man in the elevator who becomes agitated at mention of Dr. Krankheit.
- The sequence of the nurse assisting Dr. Krankheit put on his latex operating gloves is a clever reverse film of pulling the gloves off.
- In one sequence, Charles Aznavour (as the hunchback) escapes the police by crawling on the mansion ceiling and jumping down through a window made of water. This is a visual reference to surrealist Jean Cocteau's Sang d'un poète, Le (1930) where the character jumps into a mirror made of water after crawling over a hallway of doors. (The effect was achieved by constructing the "wall" and "ceiling" on the studio floor and shooting the scene from above.) Even the sound effect at that moment, a shouted "No!", is in both films.
- According to a 1969 issue of Photoplay, Pia Degermark was the first choice for the title role. Other contenders included Connie Kreski and Sydne Rome.
- Loose adaptation of Voltaire's "Candide" reconfigured for the permissive 1960s.
- The film was entirely financed thanks to Marlon Brando's participation. Marquand and Brando knew each other for a long time and were good friends. Brando agreed to do the film as a favor to his friend. He didn't particularly like the script but he had fun shooting his sequence. Then other stars agreed to play a part in the movie and it was even easier to convince the producers.
- Director Christian Marquand (with camera crew) appears briefly through reflection in mirror-walls, in the final scene, filmed outside, with all actors together.