The slip up isn't seen, but in a speech given by Al Pacino. I can't remember when the speech is given its either to Jaime Foxx or the last speech in the locker room before the big game, but Al Pacino's character is telling a story about when he played and being in the huddle having those eleven guys looking back at you. If you're in the huddle with eleven guys, then that means there are actually tweleve men on the field, and that is illegal formation.