The soundtrack for the film was provided by DJ Shadow (aka Josh Davis), who is a critically-acclaimed producer and DJ. He is notorious, however, for being very protective of licensing his music for other venues or projects, having declined many other scoring offers in the past. When a friend of Singer's saw the footage assembled to a rough cut, he suggested Shadow for the soundtrack. Singer got hold of a couple of Shadow's albums, and loved the music so much, he began to cut the music into his film without any contact with the DJ. When fellow producer Ben Freedman told him he would need the rights to the music, the duo concocted a scheme whereby they would write a note to him and give it to an attractive female friend who would go backstage after a show and personally hand-deliver it. It worked. Weeks later, the two scheduled a flight to LA to coincide with a last-minute meeting with Shadow and his agent. According to Shadow, he was prepared to turn down the men's offer to use his music. But when they showed him a rough edit of the film with his music that Singer had already cut-in, Shadow was taken aback and completely impressed. He not only let them use existing titles, but even remixed some older tracks intercut with new audio samples recorded by Singer in the tunnels as a special score done for the film.
