Chuck Jones had been under an exclusive contract with Warner Bros., and worked on this film in violation of his contract. After Warner Bros. picked up the film from UPA for distribution, they discovered his work on the film and fired him, resulting in his departure for MGM.
When Judy Garland was approached about doing this film, it was she who reportedly suggested that her two good friends (and The Wizard of Oz (1939) collaborators) Harold Arlen and E.Y. Harburg provide the music and lyrics, respectively. It was to be both men's last full-length score for any medium.
When the nefarious Meowrice hatches a plot to shanghai Jaune Tom and Robespierre and sell them as ship's cats, he escorts them to the celebrated feline cabaret, the "Mewlon Rouge", under guise of friendship. During this scene, the famous French artist Toulouse-Lautrec - who painted many advertising posters for the real Moulon Rouge - is portrayed as a bearded, green-colored cat sitting at a nearby table, tossing back a drink and sketching his surroundings.