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.
Episode #1.3 - S1-E3
Factual error: Billy is called up into a specific unit of the Royal Artillery. This didn't happen. He would first have been sent to a Royal Artillery training depot and only after training would he have been assigned to a unit.
Factual error: The judge rules in favor of Wendy's father despite not hearing any testimony from his primary witness, who fails to appear. The judge states on the record that he is making this ruling because of the Byrdes' "reputation" rather than any testimony. This is absolutely ludicrous. A judge is not allowed to make a ruling on a child custody case based entirely on his opinion of the litigants, which he doesn't even elaborate upon, rather than any evidence or testimony before him.
Factual error: In the last 2 episodes of series 2, when anyone uses a phone box it has the the BT Piper logo on the outside, which wasn't introduced until 1991 - six years after the series is set.
Factual error: Johann Eck is dressed as a cardinal and Albrecht von Brandenburg addresses him as "Your Eminence" and kisses his ring. In reality, Eck was not a cardinal. Albrecht, however, was. It should be Eck showing deference to him, not vice versa. Albrecht was also only thirty, half the age of the actor playing him.
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: ACC Pat Gallan wears the ribbon of the Queen Elizabeth II Diamond Jubilee Medal. The medal was issued in 2012. Her medals would be correct for 2017 when the series was made, but not 2007 when it is set.
Episode #1.2 - S1-E2
Factual error: The settlers prepare to burn Verity at the stake as a witch. Witches were never burned in England or her colonies; they were hanged.