Only 3 days after the film's release In the US, it was aired on television.
This movie wasn't released in the USA until 1974, over three years after it was made. The film was shot in France in 1970 and first released around the world there on 18 December 1970.
The car that Charles Bronson and Jill Ireland drive in to get a doctor was a red Opel Commodore GS/E I6.
Jason Robards was originally cast in the role of Captain Ross, the movie's main antagonist. The part instead went to James Mason.