Conversation so far:
What can you tell me about the film Caligula's development?
Vidal's screenplay had a strong focus on homosexuality, leading Guccione to demand rewrites which toned down the homosexual content for wider audience appeal.
What idea did Guccione have in mind for the screenplay of the film Caligula?
Guccione was concerned that Vidal's script contained several homosexual sex scenes and only one scene of heterosexual sex, which was between Caligula and his sister Drusilla.
Where was the film Caligula developed?
Principal photography for the film Caligula began in 1976 in Rome.
why was the film Caligula developed in Rome
Caligula (Italian: Caligola) is a 1979 erotic historical drama film focusing on the rise and fall of the Roman Emperor Caligula.
Who was part of the film Caligula's development?
The production companies for Caligula were Penthouse Films International and Felix Cinematografica.
Who wrote the screenplay that the film Caligula is based on?
A screenplay was written by Lina Wertmüller, but Guccione rejected Wertmüller's script and paid Gore Vidal to write a new screenplay
Why did Bob Guccione reject Lina Wertmüller's script for the film Caligula?
Guccione offered directing duties to John Huston and Lina Wertmüller, both of whom rejected the film.
What else happened during the development of Caligula besides the screenplay and filming in Rome?
Several mainstream actors were cast, Guccione intending to make a film which he felt, like Citizen Kane, would be a landmark in cinematic history

Question: What were some of those actors?
Self-contained rewrite: What were some of those actors a part of Caligula?