Martha Hyer says in her biography that playing love with Lawrence Harvey needed a good stomach. According to her, he was a real life the same misfit he was in most of the films he played.
John Sturges admitted to have made the movie for money only. He did not feel the story, the characters, the whole atmosphere. Plus, Laurence Harvey's mannerism made him the shooting very uncomfortable.
John Sturges intended to show in this movie women playing some kind of male characters.