Episode #3.3 - S3-E3
Factual error: Tommy refers to Istanbul. It was always still called Constantinople in the West at that time and would be for several more years.
Continuity mistake: The first man to die in the ploughed field "execution" scene had the back of his head blown away by a gunshot. In the replay in next episode, his head shows no such effect.
Episode #3.4 - S3-E4
Factual error: John says that he has found plans in the British Library. It was only renamed the British Library in 1973. Before that it was called the British Museum Library (or commonly just the British Museum) and nobody called it the British Library.
Episode #1.4 - S1-E4
Factual error: In 1919 Chapman receives £200 from the Russian Embassy, but diplomatic relations were not established until 1924.
Episode #3.2 - S3-E2
Factual error: Father Hughes says that Admiral Hall may be detained in the House of Lords. Admiral Hall, although knighted, was never ennobled and thus did not sit in the House of Lords.
Episode #3.3 - S3-E3
Factual error: Grace suffers a gunshot wound to the upper left chest in the previous episode, and episode three reveals she died. The bullet would have passed under the clavicle and would have missed the axillary artery and all other major blood vessels. This wound should not have been lethal, especially because Grace's family immediately called for an ambulance, so she would not have had to wait long for medical treatment. Most of her family members are military veterans who would have knowledge to provide the necessary first aid. (00:01:50)
Episode #2.5 - S2-E5
Continuity mistake: The camera cuts between a wide shot and a close-up of Pol and Inspector Chester Campbell undressing her. Between scenes for the next minute, Pol's shirt is on in the close-ups but taken off in the wide shots. (00:24:40)
Factual error: Diana Mitford was never "Lady" Diana Mitford. The daughter of a baron, her title was "the Hon. Miss Diana Mitford" before her marriage. When she met Mosley, she was "Mrs Bryan Guinness."
Factual error: Moss is apparently now a chief superintendent. This rank was not widely used in England until 1949 and was not in use in Birmingham City Police until at least that time.
Factual error: Birmingham Urban District Council is mentioned. There was no Birmingham UDC. Birmingham was a County Borough with City status, not an Urban District.
Episode #2.3 - S2-E3
Continuity mistake: The bullets on the table change positions during the scene after they stopped moving. For example, when Arthur moves the glass, you see 5 between him and the glass. In the next shot, you can't see any of the bullets, even though you see the same area. They're back when she flips the table.
Visible crew/equipment: An iPhone being held by someone is visible through a window in the top left of the screen during the decoy vehicle scene near the beginning of the episode.
The Company - S4-E6
Factual error: Tommy makes a call during the episode to the USA, there was no system for international calls in 1926 for the general public, that was only introduced in 1927. (00:33:30)
Factual error: Filter cigarettes weren't conceived until 1925 and not in common use until decades later. No self-respecting gangster would have smoked them.
Episode #3.6 - S3-E6
Factual error: Tommy says that the Chief Constable of Birmingham has issued a warrant for the arrest of Arthur, John, Polly and Michael. Only a magistrate or judge can issue an arrest warrant. The senior officers of the Metropolitan Police were sworn in as magistrates, but not those of other forces.
Factual error: Arthur is "deputy vice-president" of the Shelby Company Ltd. This is an American position title that would never, ever have been used in 1920s Britain.
Factual error: The on-screen caption when Aberama Gold is in Scotland reads "Glasgow." All we see is rolling countryside, without a city in sight.
Factual error: Several characters refer to "the London Times." It's never called this in Britain. It's just "the Times."
Episode #2.5 - S2-E5
Factual error: The Metropolitan Police officers who arrest Arthur in Camden Town are wearing the spiked helmets of the Birmingham City Police, not the boss-topped helmets of the Metropolitan Police, which we do see at other times.
Factual error: The Russian grand duke is called Leon Petrovna. Petrovna (daughter of Petr) is a patronymic used by a woman. A man would use Petrovich (son of Petr).
