Continuity mistake: When Mary first opens the phone book at the post office she lands on Finklestein but when she puts her finger on the name she chooses it as Hororwitz, even though she never turned the page again.
Other mistake: When Max is reading the note Mary left on the first page of her book, the words Mary speaks continue on the next page, but Max never turns the page.
Plot hole: According to the phone book the name given was "M. Horowitz" but when Mary mails he first letter to him she already knows it's "Max."
Max Jerry Horovitz: It would be good if there was a Fat Fairy. She would be a bit like the Tooth Fairy but would suck out your fat.
Narrator: Max hoped Mary would write again. He'd always wanted a friend. A friend that wasn't invisible, a pet or rubber figurine.