Other mistake: When Bobby recovers the onside kick, he recovered it on the 43-yard line, which is where the ball is spotted (the scoreboard even shows this). However, there was an unsportsmanlike conduct penalty with the late tackle (and a flag was thrown so we know the ref didn't miss the penalty) so the ball should have been spotted on the 28-yard line. (And there's no question there were no off-setting penalties).
Other mistake: At the beginning of the movie when Bobby starts being waterboy for Coach Klein, the players are on the field giving him a hard time. Bobby is on the sideline and the quarterback is making fun of him, which winds Bobby up and he runs onto the field tackling the quarterback. Even though Bobby hits him from the front, knocking him onto his back, a clump of grass somehow appears in the quaterback's facemask.