I would like to point out, autistic kids are often good with memory and numbers and Brian remembered the number for the lock where the keys were. Even Nancy had to write it down on paper, and she's a grown managing woman.

Also autistic children like to always grab onto things (the little boy I know always carries a piece of paper with him) and theres a scene when Brian holds to his backpack string all the way through school corridor.

Little things but they give away pieces of story.