First appearance of Castle's "Writer" Kevlar vest.
Castle refers to Vodun, not voodoo. The experts say that Vodun is a religion with a wide variety of serious spiritual beliefs and that voodoo, on the other hand, is what Hollywood directors speak of when they want to make a movie with curses and zombies.
Nathan Fillion (Richard Castle) and Darby Stanchfield (Meredith) play characters who were previously married to one another. In the movie Waitress (2007), they played husband and wife.
Nathan Fillion played "Malcolm Reynolds" in the series Firefly (2002); in the episode "Our Mrs Reynolds" Malcolm is advised that sleeping with a character, who happens to be a red headed antagonist, will result in him going to a "very special kind of hell" the same line Castle uses to describe living near his equally antagonistic and red headed ex-wife.
Given Castle's frequent comic book references this episode has two Easter eggs. Loren Lester (Mr. Simmons) voiced Dick Grayson/ Robin /Nitewing in Batman: The Animated Series. ALDIs Hodge would go on to play Hawkman in Black Adam (2022).