About 20 minutes in, there is a postcard on the wall of papers that John and Mary are looking through that's titled "Manners Motel." This is an obvious nod to Kim Manners, who produced 78 episodes and directed 17 episodes of Supernatural (2005) until his untimely death in 2009. Jensen Ackles, who produces and narrates The Winchesters, was one of the stars of Supernatural. Kim Manners' catchphrase "Kick it in the ass" was used many times in that show.
Mary nicknames John Winchester soldier boy. Jensen Ackles who plays their son Dean who narrates the show also appears on the superhero show The Boys where his superhero name is Soldier Boy.
The episode ends with an in memoriam to Lou Bollo.
In the pilot you can see D.Nutter on the folder. An homage to the director of the Supernatural pilot, David Nutter.