Tanngrisnir

Hunt - S5-E16

Character mistake: Beckett identifies the area given for the Skype call as the whole city of Paris. It's hard to believe that Beckett knows the area of a foreign city by heart, the problem is also that she is wrong. Paris actually has an area of about 105 km² (41 sq mi).

Tanngrisnir

Dead Red - S8-E11

Character mistake: Castle claims that they are technically standing on Russian soil inside the consulate. Contrary to popular belief foreign diplomatic missions, while being afforded special privileges (ie. Diplomatic immunity), are not considered sovereign territory of the represented state. Because of that Castle and Beckett are in fact on U.S. soil.

Tanngrisnir

Room 147 - S6-E16

Plot hole: All three murder suspects claim to have seen a picture above the fridge of the hotel room. This picture however is only in the hotel room where the actual murder happened, not in the room that is shown in the video, so they couldn't have seen it.

Tanngrisnir

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.

Tanngrisnir