Pilot: The Spirit of Christmas (Jesus vs. Santa) - S1-E1
Revealing mistake: Each time Jesus turns his head to speak to the children when he is beating Santa Claus, he has two left arms.
Revealing mistake: Dead lady blinks when Barnaby enters the room.
I Guds namn - S3-E8
Revealing mistake: After Beck has arrived at the coroner we see Margareta Oberg's body on a table. Looking closely you can see she's still breathing.
Revealing mistake: Creek reads a newspaper article about Tracy, a missing schoolgirl. The first paragraph of the article is about the schoolgirl, but the rest is about John Major (who had just been ousted by Tony Blair as prime minister when the episode was first aired, but, assuming this was filmed some months earlier, would still have been in power). The first line of the article following the first paragraph starts mid-sentence, as if the first paragraph has simply been pasted over the top of the existing article. This mistake is surprising as there is a photograph of John Major alongside the article and the newspaper remains in shot long enough for it to be spotted without the need to pause the DVD or video.