The film was shot mostly in England. After losing a huge amount of money from its American release, the film was released in Britain about a year later. It was also cut from 155 minutes to 137 minutes. Janet Suzman's role was cut out completely, though her name was still prominently displayed in the opening credits.
Laura Gemser, popular star of the Emanuelle and other sexploitation films, has a minor uncredited role. Director Stuart Rosenberg said he wanted an actress who looked Cuban and personally chose her, even though she's Indonesian. She later called the experience "unreal" and said she enjoyed working with all the major stars, but unfortunately had no lines. She was just Orson Welles' character's arm candy.
At one point, Yugoslavia was considered as a shooting location. Yugoslav producers found locations to play Hamburg and Havana. The only ship they could find that fit the U.S. producers' specifications was being destroyed in a harbor, so the idea was abandoned.