Factual error: Nick tells fellow vampire Aristotle, "You still owe me for that time at the Battle of Hastings." Nick was brought across in 1228, or so the intro told us every week. The Battle of Hastings, as any British school kid knows, was fought in 1066, over 100 years before Nick's mortal birth. (00:29:30)
Heart of Ice - S1-E3
Other mistake: When Batman is watching the security footage of Victor Fries' accident, at first Fries is addressing the camera directly which follows him and pans according to his movements and Ferris Boyle interrupting him, which would suggest a second person was in the room with a handheld camera. But after Ferris Boyle enters the room and orders Fries' experiment terminated, there are several cuts from various angles in the room suggesting surveillance cameras. The surveillance style footage also often conveniently cuts to the face of whichever person happens to be speaking or will cut to a certain angle in order to put emphasis on the action, all of which would require multiple mounted cameras and purposeful editing by either Boyle or one of his subordinates, which would be completely illogical since they don't want anyone to see the footage in the first place. (00:12:20 - 00:13:55)
Near Death Experience - S12-E1
Revealing mistake: At the end Jack wrestles the knife out of the attacker's hand and in doing so cuts his own hand. However in the extreme close up you can see the rubber knife is bending when Jack wrestles it away. (01:30:30)
Sex, Drugs and Rockin' the Cradle - S3-E14
Visible crew/equipment: The tip of a boom mic is swinging in the upper left of the screen during a late scene between Amanda and Peter. (00:32:13)
Factual error: In many episodes, cars which are said to be owned by a character have a Certificate of Fitness on their windscreen. Private passenger vehicles in New Zealand under 3.5 tonnes have a Warrant of Fitness, not a Certificate of Fitness. This means these cars are most likely rentals.
The Patience of Maigret - S1-E1
Other mistake: A newspaper headline reads "MAIGRET tient t'il enfin le tueur?" This makes no sense in French. It should read "MAIGRET tient-il enfin le tueur?" ("Does Maigret have the killer at last?"). (00:27:55)