Debut theatrical feature film as an actor of Woody Allen. The picture was also Allen's first ever produced screenplay as a screenwriter with the DVD sleeve notes stating "Woody Allen's debut script".
Dr. Fassbender's line about Rita "knowing James Bond" was ad-libbed by Peter Sellers, which explains why Ursula Andress laughs out loud afterwards. Andress played Honey Ryder in the first James Bond film, Dr. No (1962).
During shooting in Paris, Paula Prentiss suffered a nervous breakdown. She climbed up to a catwalk and started walking the beams. She loudly called down to everyone on the set, "I'm going to jump." She did, but a French technician grabbed her, and saved her life. She was transferred to a clinic in New York for recuperation. It almost derailed her career. She didn't turn up in another movie until Catch-22 (1970) five years later, though she did appear in episodes of TV shows.
Actor-writer Woody Allen once said that Peter Sellers gave himself all the best lines in the picture and so after this film Allen wanted more artistic control and became a director. Frank Miller at the Turner Classic Movies website states that Sellers "started improvising his own lines and suggesting added scenes. Even more damaging, he and Allen developed a rivalry that wasn't helped by their resemblance to each other. Sellers resented people's mistaking him for the neophyte actor-writer. And it got worse when an executive producer on the film, thinking he was Allen, reassured him that he wouldn't let Sellers damage his picture. Sellers began improvising more and even got the producer to give him lines and scenes Allen had written for himself. Suddenly Sellers was the film's star, and Allen was reduced to a supporting role."
Richard Burton: Uncredited, as man in a strip club. Burton appears with Peter O'Toole in a scene in a bar where Burton asks O'Toole, "Don't you know me from someplace?" O'Toole responds: "Give my regards to what's her name." The dialogue is a reference to their appearance together in Becket (1964), and to Burton's wife at the time, Elizabeth Taylor.
Louise Lasser: Uncredited, the soon to be wife of the film's writer and co-star Woody Allen, as a masseuse. Allen and Lasser would collaborate on a number of projects during the mid-to-late 1960s and early-1970s including Bananas (1971), What's Up, Tiger Lily? (1966), and Take the Money and Run (1969).