Castle's mother, played by Susan Sullivan, is a long-time struggling actress. In the episode "Tick Tick Tick" she watches herself in the pilot episode of The Incredible Hulk, in which Susan Sullivan appeared.
Castle's character in the Nikki Heat book is Rook. In chess, a rook is the castle piece.
This episode, and its followup, reunites Nathan Fillion and Dana Delany who previously played a married couple on Desperate Housewives (2004) during the show's fourth season.
Dana Delany and Stana Katic have both voiced Lois Lane in an animated movie.
Both Nathan Fillion and Leonard Roberts appeared on Buffy the Vampire series, though in different seasons.