Larry got most that I can remember…
However, SRL was in the fighter, as was Jones (the announcer from the actual fight) and technically (end credits) Mickey Ward was in it too.
Speaking of SRL, he was also involved in the filming but not in (that I know of) Reel Steel.
Roy Jones also had small roles in the new Universal Soldier, Little Fockers, New Jersey Turnpikes, and in the Devil’s advocate he was fighting (I think they filmed the movie when the fight was live). Kind of like they did Rocky Balba during a Roy Jones Jr (who was initially supposed to be Mason Dixon) fight.
I can't think of any more at this time but I know there is more.