Near the end of the movie, it looks like Maximus is going to escape and rally his army to storm the city. I got all excited for the bango finale, but they backed off and threw in a stupid knife fight instead.
The ending was like "West Side Story" without the music.
I didn't mind the knife fight, because they could in principle have worked that into Roman history (not so with a storming of the city, I'm afraid). Commodus was assassinated, so in the context of the movie they could have covered up the fight with Maximus and sold it to the public as a standard coup. But they didn't bother to conform to the historical record, even with that easy out.
Pertinax, who's he? Severus who? Grumble, gripe.