The prosthetics used in fight scenes to show injuries were made to look like 1970's style grindhouse effects.
Vince Vaughn put on fifteen pounds of muscle and trained as a boxer for three months prior to walking on set. He stated that this made the fight choreography much easier to learn.
During a Q & A at TIFF, the producers commented that the destruction of the car was done by Vince Vaughn. The car parts were real and were set up in a way that Vaughn wouldn't hurt himself badly.
Upon first arriving at the prison, two separate prisoners make reference to a prison in Austria. They are most likely referring to Justice Center Leoben, which has been recognized as one of the "nicest" prisons in the world due to its modern and luxurious architecture and furniture.
Writer and director S. Craig Zahler wrote this screenplay before writing Bone Tomahawk (2015) despite the latter being filmed first.