As originally filmed, Carlotta's dog was named Mussolini. However, due to the changing world political climate of the 1930's, the dog's name was post-dubbed as "Tarzan", even though Marie Dressler's lips are clearly saying "Mussolini".
Bravely, it seems, John Barrymore -- who struggled with chronic alcoholism that would lead to his death at age 60 in 1942 -- plays the has-been actor Larry Renault, who is also addicted to the bottle. And like his character Renault, he was in the midst of ending a third marriage, which would happen within a year.
John Barrymore relished the challenge of a strong character part. He got involved in his role, making suggestions along the way, such as misquoting famous writers and botching his own suicide. George Cukor was pleased that an actor of such prominence was confident and committed enough that to sacrifice vanity for the greater success of the film. He later said, "Although (Barrymore) was playing a second-rate actor, he had no vanity as such. He even put things in to make himself hammier, more ignorant."
Marie Dressler was impressed with Jean Harlow. She recalled in her autobiography, "It was whispered behind more than one hand that Jean Harlow, Metro's much-advertised platinum menace, was picked for parts that called for more allure than art. And in Dinner at Eight, she had to throw a bomb in the works by proving that she is a first-rate actress! Her performance as the wife of the hard-boiled, self-made politician played by Wallace Beery belongs in that limited category of things which may with reason be called rare. The plain truth is, she all but ran off with the show!"
Jean Harlow got along with all of her co-stars, except Wallace Beery. She had worked with him before in The Secret 6 (1931) and the two had developed a dislike for each other that carried over. Beery thought that Harlow wasn't experienced enough as an actress and treated her rudely. Harlow found Beery gruff and boorish. Since the two were playing a husband and wife that can't stand each other, the real-life feelings worked to the comic benefit of the characters.