During one of Conrad's therapy sessions with Dr. Berger, as Dr. Berger is getting him to open up about the emotional pain he faces at home, Conrad misspeaks and says, "I'm your doctor, you're supposed to make me feel better." His intended spoken dialogue should have been, "You're my doctor, you're supposed to make me feel better."
While Conrad is watching the swim meet and fighting outside of school, he has a red plaid shirt under a gray sweater. When he arrives back at his grandmother's house and the subsequent scenes, he has a white with thin blue stripes shirt and a beige sweater.
At the beginning of the scene at the golf club, Calvin remarks how strange it is that there are no hills in Houston. Chicago and its surrounding area are extremely flat, so it's unlikely that a resident of that area would find lack of hills remarkable.