Factual error: The blue Austin A35 seen in several episodes this series is three years too early - the series is set in 1953 and the A35 started production in 1956.
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.
Factual error: The watch that Sid sold (a gift from Father Brown) appeared to have a twist-o-flex band, but they were not available until 1962.
Factual error: Mrs. Devine's Morris Minor is a 1962 model, this series is set in 1954.
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 Great Train Robbery - S7-E1
Factual error: The newspaper shown at the end, dated 31st of August 1953, has an article in it called "Enemy Claims" about the German campaign on the Balkans in 1941. (00:42:55)
The Sins of the Father - S4-E9
Factual error: Lady Felicia is asked to sing a song she would sing in church and chose "Morning Has Broken," most lately associated with Cat Stevens, but here's the catch: Prior to Cat Stevens' rework of the 1931 English children's hymn's lyrics (by Eleanor Farjeon) to the tune of old Scottish children's hymn sang in the old Gaelic: "Child in a manger, Infant of Mary, " based on a melody called "Bunessan" (written by Mary MacDonald), the 2 hymns' lyrics and tune weren't combined into the one hymn until 1972. (00:05:00)