Continuity mistake: When Beckett is interrogating the drug dealer, in shots from behind, only her right hand is on the table. In shots from the front, both of her hands are on the table. (00:09:20)
Character mistake: When the private investigator shows Castle and Beckett the VIP Liaisons website, "Liaison" is misspelled "Liason." (00:17:40)
Continuity mistake: Alexis has just walked into Castle's study and is relaying a message from his publisher to her dad. She holds the note differently in consecutive shots. (00:30:20)
Continuity mistake: Castle asks his daughter what she would do if she needed a quarter of a million dollar, just like the murdered victim. She answers that she would ask him for it. Watch her necklace. It jumps in and out of her top. (00:31:10)
A Chill Goes Through Her Veins - S1-E5
Continuity mistake: When Castle and Beckett visit Mr. Davidson, he comes out chasing his two grandchildren - a tall girl in a red jacket and another one who's slightly shorter in a light pink jacket. When the detective and Castle walk up, the grandkids have switched places. When Mr. Davidson says, "Did I scare you," Beckett has her hand in her jacket, but when Beckett says, "Mr. Davidson," her hand is not in her pocket anymore. When Mr. Davidson says, "Why don't we go inside," Beckett is putting her badge in her pocket, but in the shot before she already put her badge in her jacket. Finally, when Mr. Davidson says, "Alright!" the girls have switched places again between shots. (00:09:50)
Home Is Where the Heart Stops - S1-E7
Factual error: The shots of the West Side towards the end of the episode are reversed: you can see traffic on the West Side Highway moving in the wrong directions. (00:40:10)
Home Is Where the Heart Stops - S1-E7
Visible crew/equipment: When Castle and Beckett step into the elevator whilst talking about The New York Review of Books, a cameraman is reflected in the left door of the elevator as it closes and the scene ends.
Home Is Where the Heart Stops - S1-E7
Continuity mistake: After the two talked to the victim's daughter, Castle buys Beckett a soda. The way he holds the can as he hands the soda to her changes between consecutive shots.
Home Is Where the Heart Stops - S1-E7
Continuity mistake: When Esposito pulls up Evan Mitchell's rap sheet, it says he is 5'9", but in Mitchell's mugshot, the top of his head crosses the 6' mark.
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)
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.