Trivia: When Ryan and Esposito go to where the victim worked, the guy that talks to them was on an episode of the short TV series Moonlight where he played a guy that was stalking a girl after his death. He even tells Ryan that if he changes his mind, he'll give him some hair gel and fangs; the guy was turned into a vampire before his execution.
Trivia: This episode features numerous references and homages to 2001: A Space Odyssey. Keir Dullea, who played Dave Bowman in that film, played the father of the victim in "Flowers for Your Grave", the Castle series premiere.
Trivia: When they find a dead body in the cemetery that has been staked, Castle mentions Buffy. Nathan Fillion starred as a priest in Buffy The Vampire Slayer.
The Mistress Always Spanks Twice - S2-E16
Trivia: The woman playing Kevin Ryan (Seamus Dever)'s girlfriend is Juliana Dever, Seamus's wife.
Trivia: The voice of Oracle, the computer on the "Nebula 9" ship, is provided by Stana Katic.
Trivia: Nathan Fillion and Darby Stanchfield (Castle's ex-wife Meredith) play husband and wife in the movie Waitress.
Trivia: When Ryan and Esposito are searching for Jones the bodyguard, the man they first approach is Kris Brkljac, to whom Stana Katic has been married since 2015. (00:05:35)
Trivia: Kristin Bauer van Stratten (from True Blood) makes a cameo early in the episode as one of the operators at the phone sex business.
Trivia: Nathan Fillion and Stana Katic are close enough in age that "Flowers for Your Grave", the series premiere, aired shortly before he turned 38 and "Crossfire", the series finale, aired shortly after she did.
Trivia: Just before Beckett shows up at the loft to admit her feelings for Castle, he ignores an incoming phone call from her. The picture of her on his phone screen is the same picture of her on his digital murder board about her shooting. Not necessarily a goof, since he could simply like that picture of her, but interesting to notice.
Answer: The networks are now having winter breaks. A mid season end of new episodes, when they come back after the new year, it picks up as if several months have gone by. Beckett suggested Valentine's Day as a "chick flick" to watch as she is moved in. Also some episodes are not scheduled to air in order.