Trivia: Castle's Halloween costume is of Malcolm Reynolds, played by Nathan Fillion in the short-lived TV show "Firefly." Alexis asks him: "Didn't you wear that like five years ago?" Serenity, the film based on Firefly, was released 5 years before this episode aired.
Fool Me Once - S2-E4
Trivia: Firefly reference. In that show, two agents were sent to capture the character River Tam. The agents wore blue surgical gloves and were foreshadowed by River prophetically muttering "two by two, hands of blue." In this Castle episode, after putting on blue gloves ("hands of blue") , Castle holds up two fingers on each hand one after the other ("two by two") then opens his hands.
Trivia: After learning a murdered television host was planning on changing his show-ending signature line, Castle suggests to Beckett that they should have a signature line of their own, and suggests "A whole new chapter in crime solving." This is actually the tag line on the season 1 DVD set. The other line Castle suggests, "She's armed, he's dangerous", became the tag line on the season 2 DVD set.
Trivia: In the elevator, Castle and Beckett have a conversation about his previous relationship with Kyra that mirrors their conversation in "Little Girl Lost", with the roles reversed, about Beckett's relationship with Will Sorenson. (00:20:00)
Trivia: Throughout the episode, it's heavily implied, short of mentioned outright, that Castle is being considered to write a new James Bond novel. Stana Katic is actually a Bond girl, having had a small role as a Canadian intelligence officer in 'Quantum of Solace'.
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.
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.