When Beaver and Wally are looking at the pile of junk on the front lawn, the stains on Wally's sweatshirt are different than they were in the kitchen in the previous scene.
At the breakfast table when Ward tells Beaver and Wally that they must do yard work, Beaver's hair is distinctly divided into two large sections laying straight down on his forehead. In a closeup shot of Beaver, his hair is still down on his forehead but with one large section and a few strands where the other section was in the wide shot. As Beaver rises to leave the table, his hair now is neatly combed into one large section higher up on his forehead.