Jon Bernthal's character as Shotgun has a tattoo on his neck that says PEN1. It stands for Public Enemy No. 1. PEN1 is a white street gang from Orange County California.
After the riot Jacobs cell number is 13 same as hotel room when his son comes to visit.
The Beast, played by Holt McCallanly, says he likes to read books on psychology. McCallanly is one of the main actors in Mindhunter (2017-) which focuses on criminal psychology.
Jon Bernthal and Jeffrey Donovan both worked together before, having supporting roles, in Sicario.
Second time Ric Roman Waugh has directed Benjamin Bratt & Jon Bernthal after Snitch (2013)
It' supposed that the prison where Money and The Beast are locked is Corcoran, the same scenario than Felon, the other prison film of this director Ric Roman Waugh.
Jon Bernthal's character is Frank, nicknamed "Shotgun". Jon portrays Frank Castle/Punisher in the Marvel Cinematic Universe with a shotgun as his weapon.