M.E. Parish cuts the finger tip from a latex glove and Castle asks her, "Ever consider becoming a moel?" A moel performs the brit mila, ritual circumcision. A woman who does this is called a moelet.
When Richard and Alexis are talking about movies, he says "...but I got dibs on "A Christmas Carol"." Molly C. Quinn, who plays Alexis, voices two parts in the animated film A Christmas Carol (2009).
When Castle's mother asks if Hollywood has lost its originality, Castle mentions Asteroids being optioned as a movie but that Ryan Reynolds is slated to play the triangle, and that he is good. In the early 2000s Nathan Fillion was in a TV show with Ryan Reynolds called 2 Guys, a Girl, and a Pizza Place. Absurdly, Castle's comment turns out to have some truth to it, as Lorenzo di Bonaventura actually is developing a movie based on the video game.
Nathan Fillian was a fan favorite to play the live action Green Lantern (2011). The role went to Ryan Reynolds.
Castle compares his partnership with Beckett to that of Turner & Hooch (1989). Scott Paulin, who has a recurring role in the series as Beckett's dad, is a supporting actor in that film.