The featured house had to be removed after filming, but costume designer Molly Maginnis led a group of parents that had it dismantled, reconstructed, and enlarged to become a library for the Kenter Canyon school in Brentwood, California. The new library opened in April 2004.
Lindsay Lohan, who was 14 years old at the time of production/casting, was strongly considered for the role of Alyssa and even screen tested for it. While the filmmakers were impressed with Lohan, they ultimately gave Jena Malone the part, deciding they wanted someone a little bit older.
The writer, Mark Andrus, is a fan of the band Guster, and named the dog after the band and two of the characters (Ryan & Adam) after two of the band members. Two of Guster's songs are featured in the movie.
In the audio commentary of the DVD, Irwin Winkler stated that Kevin Kline lost about 25 pounds. He was also on a constant diet and had a trainer with him. But he was not sick. It's to let the audience think George is getting sicker and sicker.
The trivia item below may give away important plot points.
Hayden Christensen injured his hand while filming this movie. During the scene where George finally tells Sam that he's dying, Christensen improvised the punching of the wall. For subsequent takes of the scene he refused to add a pad to the section of the wall he was hitting, so his knuckles were swollen and bleeding by the time the scene was finished.