As well as Mike Tyson, a number of famous faces from the world of boxing make cameo appearances in this movie - former champion George Foreman, commentators Jim Lamply and Larry Merchant, and trainer Teddy Atlas.
Incorrectly regarded as goofs: in the flashback Woody's character has a tattoo that says Garces on his back. Later during the fight it says Peace. However you can clearly see that he had Grace changed to read Peace. Most likely due to the fact he's not with Grace anymore
The ring announcer in Cesar Dominguez's (Antonio Banderas) Garden flashback fight sequence is Bruce Buffer, brother of Michael Buffer, who is the ring announcer in the climax fight between Dominguez and Vince Boudreau (Woody Harrelson).