Audio problem: When Maximus is eating with Juba and Haken, just before he fights Tigris of Gaul, listen to the background noise very closely as the men talk. There's lots of chatter and stray noises, but amid the sounds you can hear someone yelling urgently: "Warren, Warren... Warren, ...radio." This may be the sounds of a crew member telling another regarding a radio.
Audio problem: Before the first battle in the Colosseum there is a speech about Hannibal by Cassius. He says "Ferocious mercenaries and warriors from all brute nations bent on merciless destruction conquest." As he says "Conquest" it cuts to a closeup of the gladiators. Look at the crowd in the background. They are getting up while cheering and clapping. However you can't hear anything else than the speech.
Audio problem: When Commodus and Gracchus are having their little debate in front of the senate and Gracchus says "Then perhaps Caesar will be so good as to teach us, out of his own extensive experience.". Then it cuts to a wide shot of the senate, and you can hear them laugh. However, none of them are moving their mouths, nor seems amused in any way.