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: When Jonathan is falling down the stairs when being chased by the ape, there is 1 shot where you can see it's a stunt man. Slow mo may help but is not essential.