When Maximus is about to fight Titanus, he (Titanus) is introduced as the only undefeated Gladiator. However, earlier in the film, Proximo tells Max he was a gladiator and that he received a wooden sword from Marcus Aurelius, in recognition of him winning his freedom. Obviously, he had to be undefeated and I assume, alive, to do this.

The original ending was supposed to be Max fighting Proximo (The only undefeated gladiator) until Ollie Reeds untimely demise. You would have thought the script writers would have came up with something better than switching Proximo's name with that of Titanus.