The Flashman novels, while not unalloyed comedy, are mordantly funny, and Flashy is frequently - and reluctantly - embroiled in The Slave Question. He accidentally crewed a slave ship in Flash For Freedom!, then had to pretend to be an undercover British anti-slave agent to escape the dock when the ship was captured: this unfortunately led to him being recruited by the Underground Railroad - who mistook him for the zealous stalwart he pretended to be - where he was tasked with running fugitive slaves to the North, nearly getting sold down the river himself in the process {for fornicating with someone’s wife, naturally}.
Then, in Flashman and the Angel of the Lord, he was shanghaied and dragooned into both fighting alongside and betraying John Brown at Harper’s Ferry, by abolitionists and slavers alike.
Oh, and in Flashman’s Lady he became a slave in Madasgascar, where he became the demented Queen’s favourite bed-mate and rose to the position of Sergeant-General in her army. And I’ve probably missed a couple of books.
“The Legend of Awesomest Maximus” is a truly awful comedy set in the Trojan War … it does not insult your intelligence, it assaults it with intent to kill. However, it does have some humorous play with the concept of slavegirls serving in taverns of the day, drawing parallels between them and strippers at a strip club. It probably got the feel of an ancient tavern down better than most sword and sandal movies, strictly by accident.
Now, if we can open up this thread to movies that are UNINTENTIONALLY comedic … boy, have we got some candidates for ya!
The 1940 Rodgers and Hart musical The Boys from Syracuse was a comedy with some lovely songs, but the two Dromios are described in the lyrics as slaves. That said, they move around pretty freely and talk back to everyone.
The Boys From Syracuse was based on The Comedy of Errors, which in turn drew heavily on Plautus’ comedy Menaechmi. As noted earlier, the cunning slave was a recurrent character with Plautus, and the servant who is wilier than his master is a tradition that has persisted in literature to this day.
Woody Allen wrote a play – GOD, A PLAY – where a slave in ancient Greece gets all the best lines: he wants what all slaves want (to be taller), knows the horrors of war (and so passes up chances for freedom: citizens get tortured and killed by would-be conquerors, but nobody minds people who just keep doing the cleaning) and argues against accepting the Trojan Horse (because, seriously, who needs a wooden horse that big, and what the hell are we even going to use it for?).