Continuity mistake: When Jack is in his new classroom for the first time, he sits at a metal desk. He falls with the desk when he tries to reach his book bag, which is sitting next to a broken wooden desk. Next, he sits in the same - miraculously whole - wooden desk, then proceeds to break it to smithereens.
Suggested correction: Watched several times, he moves to the desk to the left of him that doesn't have a chair attached.
Other mistake: Jack's parents were at a Halloween party when his mother went into labor. Later in the movie when he's asked by his teacher he says his birthday is September 12th.
Suggested correction: The movie doesn't specifically say this is a Halloween party. This may simply be a costume party which can and do happen multiple times a year.
As you stated, it doesn't say it's a Halloween party. In fact, there's signs in the room that say "Beaux-Arts Ball."
Continuity mistake: When Jack's mom takes him to school, she's barefoot in the front yard. The next shot at school, she's wearing shoes.
Suggested correction: She's not barefoot, you can see her shoes. They're the same ones she has on later.
