Charles Bronson?

About 20 minutes in, right after the scene where Caligula argues with Claudius and Messalina and decrees that Demetrius will fight in the arena the next day, the scene cuts to the gladiator banquet the night before the contest. At lower right of the screen, for about two seconds, a servant at the banquet table looks very much like Charles Bronson. At this point in his career he was a couple of years removed from uncredited roles but was still appearing in bit parts under his real name, Charles Buchinsky. Maybe not him but it sure looked like him.