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.
'Marc Singer' had never been a filmmaker prior to this project. He had moved underground to the tunnels as a lifestyle choice, and when he and his friends were sitting around one night, someone had said, according to Singer, "Hey we should make a film about this," and tell their stories. Singer's original hope was that the film would get some attention and help get the people out of the tunnels and into better, safer places. It did.
Singer employed his friends in the tunnels as his crew. Singer claims that these people, with no prior experience in filmmaking whatsoever, were incredible in their ability to set up lighting rigs, dollies, and electrical wiring, mostly without the use of tools or real grip equipment. To make the dolly for tracking shots, Singer and his carpenter built a rig made out of wood and metal scraps. Without a power drill, they would heat a metal rod and 'singe' a hole into the wood to put a screw or dowel in for fixture.
The film was shot on 16mm black and white film stock, not as a creative decision, but because according to Singer, a filmmaker friend had told him, "If you shoot color and you don't know what you're doing, you'll fuck it all up and it will come out looking all green or red."
Singer was permitted to use a 16mm Bolex on loan from a camera house in New York without up-to-date payments. He was given left-over film stock on a "pay-later" basis from Kodak and other resources. The lab in New York that processed his negatives and prints also granted him this favor. He began editing on a flatbed, before he was granted the use of an avid at practically no charge from a friend of a friend. He also had complete and total creative control over the project and its final cut, also a rarity.