Factual error: Both Inspector Shaw and Chief Inspector Bailie wear their medal ribbons in the wrong order. The Golden Jubilee Medal is worn first, followed by the Diamond Jubilee Medal, followed by (for Bailie) the Long Service and Good Conduct Medal.
Factual error: Harold Alexander, although his rank of major-general is correctly mentioned by the narrator, wears the rank insignia of a full general.
Factual error: In s01e08, "Q and A", when Yelena is playing chess, we see her use the touchscreen which represents the chessboard. However, the bottom left corner is a white square when it should be a dark square. The board is orientated incorrectly, even though the board on the floor isn't.