When Beckett tells Esposito to look into the banking records of the first victim, he says "As you wish" (and gets a double take from Castle). This is the same thing that Westley says to every request of the princess in The Princess Bride (1987).
"Sleeping Beauty" was played by Meghan Markle, who became a real-life member of the British royal family after her fairy tale wedding to Prince Harry on May 19, 2018, however, technically, she is not a princess. Her official titles are The Duchess of Sussex, Countess of Dumbarton and Baroness Kilkeel.
Taylor Kinney, who plays Darren Thomas, plays a werewolf in The Vampire Diaries (2009). This story starts with a possible Big Bad Wolf attack.