Revealing mistake: During the chariot race, where the contestants are riding towards the screen, tyre tracks from the camera vehicle are clearly visible imprinted in the sand. (00:20:50)
Revealing mistake: When one of the ships collides with the other, you can clearly see that the rowers being hit are dummies. (01:19:00)
Revealing mistake: There is a hex bolt holding the spikes to the chariot wheel hub. (00:14:10)
Revealing mistake: When Judah and Messala hurl their spears into the wooden beam, the projectiles follow very straight paths all the way across the room to their targets, whereas due to gravity they'd really travel curved paths, practically parabolic, requiring a skilled thrower to aim above the target. What's revealed here is that the spears were rigged to slide on thin wires, to assure that they'd hit the target on cue.