As Jim Beaver (Shelby/Drew) turns around after seeing the dog, frustrated, he says "balls". This is a nod to his character Bobby Singer's catch phrase from Supernatural (2005).
According to Graham Yost, co-writer Dave Andron gave Joelle Carter (Ava) a day in a spa as a present after shooting because of the spit moment between she and Ellen May. They had to shoot it for coverage a few times and apparently, Abby Miller (Ellen May) is a good shot.
The episode title, "Get Drew" might be a reference to "Get Shorty" a novel by series producer Elmore Leonard, made into a movie of the same name