When Charlie tells the children, "See that Jaguar in the parking lot? Maple Loops", the children are sitting on the floor.
They attempt to look out the window at Charlie's car, but the window is too high to see the parking lot.
Alan and Judith are practicing their old songs in Charlie's house and when their backs are to the camera, Judith's singing does not match her mouth movements.
A boom mic is visible several times in the corner behind Charlie's right shoulder as he is sitting at the piano in Jake's classroom during practice for the school show. The shadow of the mic is also visible beneath it, on the music stand.
When the children all bow after singing the Hammerstein beer song, the girl on the far right of the front row doesn't bow when all the other children bow. She bows on her own, afterwards.