This episode reveals that Castle comes up with his crazy theories and wild speculation just to get on Beckett's nerves.
During the scene when Castle (Nathan Fillion) and Kate Beckett (Stana Katic) are talking about who they would like to be if they were "turned", Castle mentions he would prefer to be a vampire. Nathan Fillion appeared in five episodes of Buffy the Vampire Slayer (1997) and Dracula 2000 (2000)
Josh Braaten (Kyle Jennings), Brandon Keener (Charlie Coleman) & Kevin Sheridan (Paul) all started in episodes of Criminal Minds (separate episodes)