Continuity mistake: When the girls are trying to throw Angela into the lake, she steps to the edge of the dock with Angela on her shoulder. Her toes are over the edge. There is then a cut to the counselor berating Ricky with a long view of the girls trying to throw Angela in the water. They are now back in the middle of the dock instead of at the edge of the dock. (00:59:55 - 01:00:30)
Continuity mistake: When Meg comes up to Angela, taunting her, Angela's head position and the look on her face changes in each shot.
Continuity mistake: The green wood chair the chef uses to check the boiling water for the corn changes position.
Continuity mistake: During the fight between the boys in the rec hall, the cowboy hat on the floor repeatedly changes location between shots.
Continuity mistake: During the baseball game, Ricky runs for home and slides into it. His hat flies off and he leaves without it, but at the bleachers he has it on.
Answer: Watch his first scene at his aunt's. He doesn't speak at all. Clearly Angela/Peter has had a withdrawn personality since the death of his father and older sister. So doing activities with other kids is one thing he wouldn't do, as for eating, a lot of kids don't at first if they miss home.
Rob245