Continuity mistake: When Gus heads to the bathroom at Mel's house he is carrying a bag of ice. The next shot of him, he is standing at the urinal and the bag of ice is sitting on the top left of the urinal. The next shot is from the top of the urinal, with Gus is still using it, and the bag of ice is gone.
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.