Starring: Nathan Fillion, Stana Katic, Tamala Jones, Jon Huertas, Molly C. Quinn, Susan Sullivan, Seamus Dever
Continuity mistake: In episode 2-5, "When the Bough Breaks," when Rick is talking to his mother regarding handing out her pamphlets at his book signing party, he opens his beer and throws the cap on the counter, when the shot changes you see him opening the beer again.
A Death in the Family - S1-E10
Continuity mistake: Episode 1-10, "A Death in the Family": when Agent Sorensen offers Beckett a part of the sprinkled donut, the location of where he holds it changes between shots. (00:23:50)
Close Encounters of the Murderous Kind - S3-E9
Trivia: In this episode, Castle says the words "My partner is crazy and may start firing at any moment" in Chinese. Beckett then asks him "Semester abroad?", to which he replies "Nah, a TV show I used to love". This is a reference to Firefly, a TV show starring Nathan Fillion in which characters occasionally spoke in Chinese.
Question: Before this episode, there was a Christmas episode "Secret Santa" and then there was "Significant Others" with Meredith showing up to take care of Alexis. In that episode, Beckett mentions choosing the movie Valentine's Day for a date night, causing her to lose a turn. In this episode, Castle and Beckett are celebrating their first Valentine's Day together. So, are they celebrating Valentine's Day twice? This wasn't too long after the Christmas episode and when Beckett made her movie choice, no snow was on the ground. Is this a mistake or is this really their first Valentine's Day together?
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.