When Kevin is playing softball with the adults and hits Jack with the softball, Jack is holding the right side of his head. Later when Jack shows up at the dock, his left side is bandaged.
When Wayne and Angela leave the picnic table, Kevin heaves a sigh as they walk away in the background, to the right and off screen. After the view returns to Kevin from Norma, Wayne and Angela are back in the middle of the frame, and Kevin heaves the same sigh again.
Kevin falls into the lake, but moments later he is getting a beer (which his father takes away) and he is completely dry.