Other mistake: In the final game, after Gretchen has struck out for the first time, look carefully and you will see Nelson is running out of the dug-out like he is next to bat. Then in the next scene, suddenly it is Jarrett up to bat instead of Nelson.
Other mistake: In the final game of the movie, Jerry's Lumber is deliberately making errors to let Nelson score a run. In the shot where they show Marcus as the third base coach and Nelson rounds the base to go home, you can see that he never actually touches third base and cuts it off by a few feet. (01:15:25)