Sam Peckinpah later claimed that his screenplay had been ruined by the miscasting of all three of the leading cast members.
Sam Peckinpah not only wrote the screenplay, but also was the original director. He was later replaced by Arnold Laven.
Linda Evans auditioned for a part in this movie. Director Arnold Laven told her, "That was the worst reading I ever heard". She sheepishly thanked him and headed for the door. Before she could exit he stopped her and told her he was doing another project and that she had the right qualities. The next project was the western series The Big Valley (1965).
Sam Peckinpah used at least three of the cast for his cavalry western Major Dundee (1965), which was filmed around the same time: Senta Berger, Michael Anderson Jr. and Slim Pickens.
Sam Peckinpah's Malibu house was destroyed by a gigantic fire during the preparation of the movie and Peckinpah risked his life to save the script from the fire.