Factual error: 1-1 A couple of spelling errors. A "community center" in Ceylon, a British colony, using the American instead of the British spelling. And Columbo listed as the capital of Ceylon; it's Colombo.
The Incubus - S1-E9
Continuity mistake: In episode 5, it was established that there is no road to the Jezequiel house. Robert and Max had to leave their car in the village and walk across the fields to the house. In this episode, however, Robert drives his car right up to the house with no problem.
The Heart of Lord Trash - S1-E10
Factual error: Bulstrode refers to Elizabeth I. Since it's the 1930s, there's only been one Queen Elizabeth. She didn't become Elizabeth I until Elizabeth II acceded to the throne in 1952.
The Heart of Lord Trash - S1-E10
Factual error: In the prologue, Captain Dance wears two and half rings of braid around his cuff. A British Army captain, which uniform he wears, wore two rings.
