Kirk Douglas was first choice to play the duel role of Tony Wilson/Arthur Hamilton. But he would only do it if he could produce the film and director John Frankanheimer was already doing that, so Rock Hudson accepted the role.

Ford was considered for this part, but it was given to Rock Hudson.

Director John Frankenheimer wanted to cast Lord Laurence in the film, but Paramount turned him down in favor of Rock Hudson, claiming Olivier wasn't "box-office."