In one of the final arena-scenes, where all the gladiators work as a team, Maximus get's on a horse and he has a sword. He runs someone through with the sword in a close-up and when he pulls the sword back you can see it's all bloody. Then in the next shot you see him holding up the sword....no blood on it! The third shot, a close-up again (I think it's where he throws down the sword) it's all bloody again....