Gladiator was given a turbo boost
In the 2000 film Gladiator, one of the chariots gets flipped during the battle of Carthage in the Colosseum. A gas cylinder can be seen if you look closely enough. I’m pretty sure they didn’t have those in Ancient Rome, and even if they did, we were far overdue for motorized vehicles when they finally came into the hands of the general public.
Moviegoers like to keep the film’s mystique intact by avoiding seeing artifacts and behind-the-scenes secrets like this, as they strive to mentally transport themselves to Ancient Rome.