The phone numbers that are used in this movie are not the traditional 555 numbers used by Hollywood. Actually, the number that Henry gives as his home number is for the Norfolk Baseball Academy in Virginia.
The White House postcard appears to be crooked and bent when Jeremy reads it for the second time, but it's in perfect condition when the box is filled up with liquid.
When Jeremy reaches through the tube to the interior of the car, he pulls back his hand with two knuckles scraped raw and a cigarette lighter burn on his hand. The knuckle wounds remain but the cigarette lighter burn disappears within seconds.