Audio problem: Topper is driving in to the base beside the running troops on his bike. When they recite the Brady Bunch part, none of the soldiers' mouths are moving.
Audio problem: When the Christian army is defeated after chasing Saladin across the desert, many vultures are flying over the battlefield. However, the sound is that of a flock of whooping cranes.
Audio problem: When Maximus is eating with Juba and Hagen, 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. (01:36:30)
Audio problem: Near the end of the movie the helicopter is flying into the area where the troops were held. The radio traffic isn't pilots or air traffic controllers, it's railroad dispatchers and trackside detectors.
Audio problem: During the scene where Ada and her father are talking about the farm, and how they will manage come winter, Ada says : ...."But with no-one left to work this place, nothing to buy, nothing to buy it with".... her mouth only starts moving to what she is saying half way through the sentence.
Audio problem: In the opening, Lt. Col. Daniel Kiley is following the German staff car in the scout plane. As the car swerves back and forth on the gravel road, you hear the tires squealing. This would not happen on such a road.
Audio problem: In the scene where Matthew Broderick is addressing the potential members of the 54th on horseback (right after he accepts the position), the army band is playing, but the visuals don't match the music. While we hear drumrolls, we only see single hits on the snare drums by the actors. And at least one drummer is playing in mid-air.
Audio problem: When the Mexicans begin their final attack, we see Travis call to Joe to wake him up, but if you watch closely, you don't see his lips move, you just hear "Joe."