Reportedly, Charles Bronson's salary on this picture was US $500,000.

Charles Bronson was about 49 years old when he appeared in this movie.

Jill Ireland was the real-life wife of Charles Bronson but plays the wife of Anthony Perkins.

Althoough this is a French film, all three lead actors are actually American. The rest of the cast is European. In addition, the film was shot in English.

Charles Bronson's character isn't named; he is billed in the credits as The Man or The Stranger.

The man in film's the poster with the door displayed over his head is not Charles Bronson, who plays the lead character.