Sean Connery visited the set during filming in the South of France. He was dating Diane Cilento at the time. They married the following year.
Shot on location in London and the French Riviera.
Although the BBFC website shows this as having been 120 minutes, the review in the Monthly Film Bulletin of March 1961 states 109 minutes, which ties in with the advertised programme times from its February 1961 UK release on the ABC circuit.
Dr. Prade takes a cigarette and offers Mrs. Colby one as well, explaining that he is a psychiatrist and not a medical doctor. When asked whether cigarettes cause cancer, he merely says, "I don't know... "; the confirmation of the link between smoking and lung cancer was announced the year after this film was released.
The Colby's car in France is a 1960 Jaguar XK 150 drop-head coupe. In excellent condition in 2023 an example of this car could be worth over $120,000.