More than thirty years after this movie's release, writer and director Sir Peter Ustinov reflected that the romantic aspects of the story hadn't really worked, because Sophia Loren and Paul Newman strongly disliked each other.
In this film, Paul Newman plays an anarchist who plans to assassinate Prince Otto of Bavaria. Sir Peter Ustinov later would be present at an assassination himself, that of India's Prime Minister Indira Gandhi on October 31, 1984.
This is the first of the many English-language movies made by French star Philippe Noiret (Ambroise Gérôme). However, although he spoke English extremely well, he was dubbed in this movie (by writer and director Peter Ustinov).
Writer and director Sir Peter Ustinov claimed that an earlier attempt to film Romain Gary's best-selling novel had foundered because it presented the story as a romantic melodrama, whereas he saw it as an absurdist comedy. After it had proved to be a box-office failure, he remarked that this movie had a most unusual problem. He'd been given too lavish a budget, rather than too small a one, as on his previous movie, Billy Budd (1962). He had aimed, he said, at "a cross between René Clair and Preston Sturges", but this movie was too grandiose to be as funny as he'd intended.
This movie was originally intended as a comedy vehicle for Tony Curtis, Gina Lollobrigida, and Ralph Richardson, with George Cukor as its director. A personality conflict between Lollobrigida and Cukor contributed to that version being aborted.