Ben Gaffney (Devin Ratray) is based on a real high school friend of director Jeremy Saulnier. Saulnier contacted the real Ben while he was writing the script to get an accurate representation of Ben's moral views, and gun collection.
At one time Benny mentions a "Duce" who got hit by a train. This is a reference to "El Duce", lead-singer of punk-Hardcore band "the Mentors", who claimed Courtney Love offered him $50,000 to kill Kurt Cobain. He appeared in Nick Broomfield's "Kurt and Courtney" documentary. He died under mysterious circumstances after he made these claims.
Ben Gaffney has a tattoo on his left inner forearm of an electric chainsaw which is a reference to Jeremy Saulnier's film Murder Party (2007).
Blue Ruin is a reference to the blue and ruined Pontiac, the car-home of Dwight.
Saulnier funded production on the film through a successful Kickstarter campaign, which MTV called "the perfect example of what crowdfunding can accomplish."