In the scene where Billy is holding a guitar right after he has been sleeping on the couch where he has been what appears to be sleeping in a storage shed, it shows a fire dancer charm hanging from the end of his guitar. This is the trademark symbol for the Dave Matthews Band.
The book Maggie hands Clayton to read when he says the tv"sucks" is "Where the Red Fern Grows". Dave Matthews plays Will Coleman in the 2003 movie adaptation of the book.