Factual error: The British Army had no female soldiers in the mid-1920s. Queen Mary's Army Auxiliary Corps was disbanded in 1921 and no women served in the army from then until the formation of the Auxiliary Territorial Service in 1938.
Character mistake: Mosley says Tommy won the Distinguished Service Medal. This was a naval decoration. Tommy actually won the Distinguished Conduct Medal. Not a mistake someone like Mosley is likely to make.
Episode #3.4 - S3-E4
Continuity mistake: The show opens with an elk grazing, a shot is fired and a deer falls dead on the ground. The antlers are different - not those of an elk. (00:00:20)
Episode #3.2 - S3-E2
Factual error: Patrick Jarvis mentions Tbilisi. Nobody in Britain would have called the city by that name in 1924; it was still always referred to as Tiflis.
Other mistake: The Birmingham police officer, Moss, is still listed in the credits as Sergeant Moss. He held that rank in Season 1, but in Season 2 he wears inspector's rank insignia. Campbell does address him as Mr Moss, the correct title for an inspector.
Episode #1.4 - S1-E4
Factual error: When Freddy and Ada return to Birmingham from London they are seen on a boat called Kennet. This is a wide boat (i.e. almost twice the width of a 7 ft narrowboat) which could not have made its way from London to Birmingham in 1919/20 as all of the locks were narrow locks (7 ft) at that time.
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 #2.6 - S2-E6
Factual error: The field marshal is wearing a revolver to the Derby. British soldiers are only ever armed on duty, certainly not when attending social events. He also wears his Sam Browne outside his shoulder strap instead of beneath it; no officer would do this.
Factual error: Major Campbell heads the Irish branch of the secret service, but reports to Winston Churchill, the Colonial Secretary. The Colonial Office had nothing to do with Ireland, which at that time was part of the United Kingdom.
Episode #1.3 - S1-E3
Factual error: When attempting to arrest Grace one of the supposed IRA men proclaims that he is taking her into custody "on behalf of the Irish Free State." The term "Irish Free State" was not a term used by republicans or generally until the Anglo-Irish Agreement which led to the end of the War of Irish Independence and the establishment of the Irish Free State in 1922. Anyone representing the IRA would have, when speaking English, referred to the Irish Republic at that time.
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 #1.4 - S1-E4
Continuity mistake: Thomas and Grace are sharing a drink to celebrate her employment with the Shelbys. Thomas pulls out a cigarette, puts it in his mouth (correctly), and then turns to the camera to reveal a backwards cigarette. (00:43:00)
Episode #1.3 - S1-E3
Factual error: One of the men who approaches Tommy claiming to be representatives of the IRA sings the song "The Boys of the Old Brigade." The song is told from the perspective of an elderly veteran of the Irish war of independence which had only began in January of 1919 which had happened only 3 years before. The song was written by Paddy McGuigan of the band Barleycorn in the 1970's.
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.
