Nanny McDead - S1-E2
Factual error: The establishing shot of the building where the murder takes place features on the foyer quite prominently "715 - The Langham." The story takes place in New York, but The Langham (named after the famous British hotel) is the name of a residential building in 715 S Normandie Avenue in Koreatown, Los Angeles, used in this episode. There is a hotel by that name in New York, not an apartment building, on 5th Avenue. (00:01:00)
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)
Factual error: In the beginning of the episode, the neighbors do not hear shots fired because the murderer uses a homemade silencer. At the end, when they find the murder weapon in the dumpster at the murderer's apartment, it is a revolver. Silencers (homemade or otherwise) do not work on revolvers because the gas escapes from the sides, not exclusively the end of the barrel.
Factual error: The con is said to be electrocuted. But the jump start cables are connected to handcuffs which would short the electrical circuit and most probably melt the handcuff chain, but wouldn't electrocute the victim. (00:02:50)
Factual error: When Castle and Beckett go to talk to the victim's assistant, there is a chalk outline on the floor where the body was discovered. Although it's common in police dramas, chalk outlines are not actually police procedure, because it contaminates the crime scene. (00:08:40)
Factual error: On the way to the Hamptons, Castle's car is driving on the left side of the road, even though they're in the US (where people drive on the right side of the road). (00:03:10)
Factual error: The team is discussing the location of the Widmark hotel which the detective says is downtown. Beckett then looks at the map and locates it only 5 blocks from E 72nd street, which is UPTOWN in NYC. Furthermore the map shows E 72 intersecting Broadway which is on the west side of Manhattan. This entire mapping exercise is incorrect.
Smells Like Teen Spirit - S6-E15
Factual error: German bearer bonds would never have English writing on them, and furthermore instead of just saying "German bearer bonds" the company or other entity that issued them would be named.
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.