Episode #2.4 - S2-E4
Corrected entry: Tommy Shelby says that he is exporting whisky to Halifax, Nova Scotia, which is under prohibition, as is all of Canada and the United States. There was no prohibition in Canada. Not a mistake a businessman as astute as Shelby is likely to have made, especially as he's based his whole business plan on it.
Correction: This is incorrect. In March 1918 Ottawa stopped, for the duration of the First World War, the manufacture and importation of liquor into provinces where purchase was already illegal. However, prohibition was too short-lived in Canada to engender any real success and was not strongly enforced. Individual provinces repealed the law over the next 5 years starting with Quebec in 1919 through to Nova Scotia in 1930.
Episode #2.2 - S2-E2
Corrected entry: Solomon says he killed an Italian soldier in the trenches during the war. Italy was a British ally during WWI. While Italy fought the Austrian-Hungarians, they did not fight in France or Belgium.
Correction: Italians did fight in France and British soldiers did fight in Italy and in the Balkans alongside Italians, so many places where they could have met. Solomon never said he was killing an enemy, just an Italian.
Correction: Except Season 2 occurs in 1921-22, well after Prohibition ended in Canada.