Disappeared a few years after release and included in BFI's "most wanted" list of missing feature films in 2008. Negatives mysteriously showed up in 2014.
According to Angela Pleasence, Marie-Paule Mailleux was the director's girlfriend at the time of shooting. Larraz would have Cora do unexpected things like stick her tongue in Helen's ear to unsettle Pleasence.
All of the clothes Angela Pleasence wears in the film were her own.
Jean Seberg was originally cast in the role of Helen Ramsey, but was forced to drop out of the production last-minute due to the fact that she was not a member of the Actors' Equity Association. Françoise Pascal, Candace Glendenning, Mary Maude, Lynne Frederick, Anna Palk, Judy Matheson, Lalla Ward, Olivia Hussey, Helen Mirren, and Mia Farrow were all rumored to be possible replacements for the character before Angela Pleasence was cast.