The Realtor sign in front of Joe's house has an actual phone number of 312-257-2738 for Curtiss Real Estate on it instead of the usual 555 exchange. The 257 exchange is invalid for the Chicago 312 area code.
Alison Lohman had a small role as a cancer patient but was cut out of the movie. Since she shaved her hair off for the part, she had to wear a wig throughout her next movie, White Oleander (2002).
As Darrow is opening the door to the kitchen, after the scene with the swinging ceiling light, a woman wearing a white long sleeve V neck blouse is visible, standing in the hall behind him.
Near the end, when Joe is in the submerged school bus the water is calm and the bubbles from his nose rise gracefully toward the surface. However, the bus is supposed to be in quickly moving rapids at the bottom of a waterfall. Visibility would be near zero, and he should be fighting the current (which he is not).
When Mrs. Belmont gives Joe a package that came in the mail, it is addressed to "Dr. Emily Darrow". When we see the package again in a later shot, it is addressed to just "Emily Darrow".