The Crackpot of the Empire - S4-E4
Continuity mistake: When Eve gives Jacob a ride in her car, she says "Sorry for the bare feet, I can't drive in heels." She has no nylons on. When they get to the old building, Eve gets out of the car wearing black nylons and heels.
The Curse of the Aesthetic - S8-E8
Continuity mistake: When the nanny is found dead, the ball of wool in the bag is yellow but later on when Father Brown picks up the wool out of the bag it is grey.