According to an interview with Richard Donner, Donner was reportedly called by Charles Bronson if he wanted to direct the film, and was delivered a script, read it and thought it was interesting and eventually directed it. However, Donner felt he was still inexperience to direct a film nor did he did get along with Bronson at all, as they thought differently of how the film should have been like.
Norman Thaddeus Vane based his script on his brief scandalous marriage to actress Sarah Caldwell. Caldwell was only sixteen while Vane was thirty-eight when they got married.
First appearance of actress Jill Ireland in a Charles Bronson film. The two were married in 1968.
The voice of Jack Hawkins, whose larynx was removed in the late 1960s, was provided by an unnamed actor.
Producer Clive Sharp died on August 14th 1969, after the film was completed but before its release.
In this film, the British comedian Jimmy Tarbuck plays a character called Norman Vaughan, and the British comedian Norman Vaughan plays a character named Jimmy Tarbuck.