Mansions of the Gods, The (Asterix) - Which Circus?
On page 24 it shows a picture of the Circus Maximus and a plaque saying that the raffle will be drawn at the end of the gladiators' fights. The Circus Maximus was used for Chariot racing and not Gladiatoral Combat.
The Asterix Comics are known for not being 100 percentely historical correct.
For example, the biggest and most famous "mistake" among them all is the suggestion, a single village could have been hold up defiance against the roman conquerors, because it didn't. Caesar in fact DID overcome all of Gaul!