O'Nan wrote a majority of the songs on Brooklyn Brothers with additional songs written by Brendan Leach and Keith Freudenberger, who helped inspire the musical style at the center of the film.

Several songs from the album appear in the film, such as "Come On Girl," "278 (Airport)" and "Someday." Other tracks are new versions of songs from the film ("Faster Than Aeroplanes," "Hey Captain"), as well as completely new songs that were recorded after the film ended ("Why Don't You Cry About It," "Bravery I Can't Brave").