Rock band Art of Dying's frontman Jonny Hetherington wrote and performed the theme song, also called 'Hired Gun' with Five Finger Death Punch guitarist Jason Hook. The song plays over the closing credits in the film.
Drummer Liberty DeVitto has a daughter who is an actress. Torrey DeVitto has several credits, including Pretty Little Liars and a six year run as Dr. Natalie Manning on Chicago Med.