Federico Fellini claimed that he cast Donald Sutherland because the actor had "the eyes of a masturbator".
Donald Sutherland, who wore a prosthetic nose and chin, shaved off the front part of his hair, once telling a laughing crowd "When Fellini says get a hair cut, you get a hair cut."
Federico Fellini had to re-shoot parts of this movie, including the elaborate Venice carnival scene, when several reels of film were stolen at the Technicolor labs of Rome, on August 17, 1975. Some reels of Pier Paolo Pasolini's Salò, or the 120 Days of Sodom (1975) and Damiano Damiani's spaghetti western A Genius, Two Partners and a Dupe (1975) were also stolen. Apart from the re-shoots, this theft also forced Fellini to abandon a sequence featuring Barbara Steele. The negatives were found again in May 1976.
The sea in the film was created from cut-up black trash-bags; Federico Fellini wanted to put high emphasis on the plasticity of Casanova's life and journey.
Donald Sutherland credits Federico Fellini's The Road (1954) as one of his best and the reason he knew Fellini was a genius.