Jack's shirt turns red when leaving school on the day of the basketball game.
When Jack first goes to school and sits down in his desk for the first time, you can see his book bag and a broken desk to his right. In the next shot, he reaches for the book bag and falls over. A second later, the desk is shown breaking as he sits in it - the same desk that could originally be seen the first time he sat down. The scenes appear to be reversed.
Dolores reaches into her bag to get out the chocolate mousse for Louis; in the next scene she reaches into it again.
When Jack comes down the stairs in a cardboard box, he lands on a hardwood floor at the bottom of the staircase. When his mom sits down on the stairs, a runner is shown at the bottom of the staircase.
When Louis stops Jack after school to ask for a favor, Jack is wearing a pink shirt under his jacket. When Louis takes him aside just before he meets Louis' mom in the courtyard, his shirt has changed to red.
Jack ages at four times the standard rate and has always been this way. This doesn't necessarily mean that all his metabolic functions have been so accelerated. For example, it's OK if his beard doesn't grow at four times the standard rate.
When Jack is talking with Dolores, he puts his hands up his shirt and you can see the wire for the Lavalier microphone.
Visible during the scene in the cafeteria.
In classroom scene when Jack is being introduced to the class.
Jack tells his class that his birthday is September 12, but his parents were at a Halloween party the night he was born.