- California Doubling: The film is set in Venice, France, England and Austria, but was entirely filmed at the Cinecittà studios in Rome.
- Celebrity Voice Actor: Michel Piccoli dubbed Donald Sutherland in the French version.
- Dueling Works: With Salò, or the 120 Days of Sodom, which was also released in Italy in 1976. Both are Italian films that explore debauchery as Central Theme (or at least a character who's famous for this in Casanova's case), and both are based on the writings of a famous libertine figure of the 18th century — Giacomo Casanova's autobiography on one hand and The 120 Days of Sodom by the Marquis de Sade on the other. Salò goes full throttle and Up to Eleven with the debauchery/depravity, while Fellini's Casanova is made of Lewd Lust, Chaste Sex and Sexy Discretion Shots. Also, both films were produced by Alberto Grimaldi.
- Dyeing for Your Art: Donald Sutherland had to partially shave his head for his role.
- Fake Nationality:
- Canadian actor Donald Sutherland as Italian (Venetian) Giacomo Casanova, and French actress Mary Marquet as his mother.
- The French Marquis Du Bois was played by Daniel Emilfork, who was Chilean of Ukrainian Jewish descent. Fellini cast him because he really Looks Like Orlok.
- The giant Sandy Allen was American, her character (Angelina) likely was not.
- Referenced by...: Some parts of the film's soundtrack composed by Nino Rota are featured in Red Dead Revolver and I'm Not There.
- Same Language Dub: The non-Italian actors had to be dubbed in the film's original version.
- Troubled Production:
- Federico Fellini and the film's initial producer Dino De Laurentiis disagreed on a number of points, including the budget and who to cast for the main role. De Laurentiis bowed out from producing the film. The young Andrea Rizzoli took over, only to leave as well. The third producer to take over the project, Alberto Grimaldi, tried his best to mitigate the costs and demanded that the picture be filmed in London. Fellini refused as he wanted the production to remain in Rome. Grimaldi eventually accepted, but only at the condition of filming it in English for the international market.
- Fellini and Grimaldi did not get along on the set, due to the inflating budget and Grimaldi cutting out entire scenes and firing a lot of people from the crew because of this. So much so that filming came to a halt at some point. Filming resumed when French producer Daniel Toscan du Plantier entered the scene to co-finance the project.
- Fellini had to reshoot large parts of the film because thieves broke into the Technicolor labs of Tiburtino in Rome and stole seventy reels that amounted to the first three weeks of shooting. The thieves actually aimed at stealing Pier Paolo Pasolini's Salò, or the 120 Days of Sodom.
- What Could Have Been:
- The film's original producer, Dino De Laurentiis, wanted the film to be an academically filmed biopic that would star a beautiful actor as Casanova and emphasize his sexual exploits as main drive for an Epic Movie. Why he asked Federico Fellini of all people to make it outside of wanting to attach a prestigious director's name on it is anyone's guess. Massive Creative Differences ensued, Fellini pulled in all the weight of his Auteur License and did not budge from wanting to make it the way he wanted (very much not like De Laurentiis wanted), and De Laurentiis ended up exiting the project.
- Fellini's original script was very brutal on the historical figure owing to the disdain he had for the man. It wasn't until Fellini shot the scene of Casanova and the nun that he began to sympathize with Casanova's inability to love, giving him the character of the mechanical doll and the dream ending.
- Entire planned scenes had to be scrapped for budget reasons, much to Fellini's chagrin.
- Producer Dino De Laurentiis wanted Robert Redford in the role of Casanova but Fellini refused to cast him. De Laurentiis then bowed out.
- Marlon Brando, Al Pacino, Paul Newman, Jack Nicholson, Marcello Mastroianni, Alberto Sordi and Gian Maria Volonté were also considered for the main role.
Trivia / Fellini's Casanova