Episode #3.6 - S3-E6
Continuity mistake: Michael picks up the cash from the table. After Polly speaks to Tommy she turns around to take the money out of Michael's hand; in the shot Michael is holding the cash in his lap with his jacket off, but when Polly takes the cash it shows her hand taking the money from Michael with him wearing his suit.
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.
Episode #3.6 - S3-E6
Factual error: The locomotive used to pull the train is a LMS Black 5. This class of locomotive was not built until 1934, 10 years after the year this episode is set in. (00:32:25 - 00:32:55)
Answer: There has never been prohibition in England. There are many reasons for running an underground distillery. It would be a way to avoid things like government regulations, safe distilling methods, alcohol content limits, taxation, fix pricing, and so on.
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