At the start of the episode, Hap picks up an LP with a bullet hole through it. The LP is Mama Tried, by Merle Haggard, who died on April 6th 2016, the day that this episode first aired.
When Soldier is yelling at Hap and Leonard at the beginning of the episode, one of the things he says is, "Hap and Leonard, come out and play!" This is an often misquoted line from The Warriors. The original quote, repeated by David Patrick Kelly, is "Warriors, come out to play!"