Continuity mistake: Right before Wendy sends the email that her husband is dead, a can of shaving cream can be seen on the right side of the sink. After hearing her husband come into the hotel, she knocks over the can of shaving cream, which is now on the left side. (00:47:05)
Factual error: In several different episodes characters are escaping on foot to Canada, as evidenced by Ontario license plates. But the show is set in New England, and the only way to get to Ontario through the Eastern United States is by crossing a major body of water: The St. Lawrence River, Lake Ontario, The Niagara River, or Lake Erie. You can't walk there.
I Surrender - S1-E10
Continuity mistake: When Asha is in the hospital, her hair is pulled back and towards her right, away from the wound and a lot of her hair is next to her right shoulder. In the next shot of her, her hair has changed position.
Episode #2.1 - S2-E1
Factual error: Season 2 is set in 1979. Bill Tench and his wife are leaving the church and going to their car. Behind their car is parked a 1981 Chevrolet Celebrity.
Factual error: The provincial police is always described as the Ontario Police Department (OPD) instead of the correct Ontario Provincial Police (OPP).
Factual error: DI Renton is a Metropolitan Police officer 'parachuted' into Kent to solve a big case. This hasn't happened for many decades. Local police forces investigate their own crimes without help from the Met.
Factual error: When Detective Inspector Sara Lunt's photograph in uniform is shown on the TV news she is wearing a double row of silver lace below her hat badge. Only chief constables wear this insignia, well above the rank of inspector.
Episode #4.9 - S4-E9
Factual error: Renate escapes from the prison in a Morris Ten Four, with the badge visible on the bonnet. However, this designation was not introduced until 1935 and the episode is set in 1931.