Beaver's gym coach is wearing a left-handed baseball glove on his right hand.
When Beaver is practicing to hit the baseball in the dark, cars are going up and down the street in daylight.
When Ward finds Beaver at the park and bends down to pick up Beaver's jacket, there is an obvious voice-over of Ward's next line.
The first time they practice batting the home plate is in the sun then in the shade back and forth.