A title card references the year of the blockade as 1809. Great Britain and Sweden were allies in 1809, so there was no blockade. However, after she was forced to make peace with France after losing The Finnish War and the Pomeranian War, Sweden declared war against Great Britain. The Anglo-Swedish War (1810-1812) existed only on paper: British ships were still allowed to dock on the island of Hanö and trade with the Baltic states. Great Britain blockaded Sweden during World War I.
Vigen and the inmates from Denmark-Norway are released from prison by King George III in 1814 after an accord is reached. Sweden remained neutral in the Napoleonic Wars after her defeat in the Pomerania War (1810); Denmark-Norway was neutral throughout.
As a title card states "years went by" until Vigen encountered The Lord, only one of two flags could have been raised by the yacht: the 1814 or the 1821 merchant flag of Norway, neither of which had the union mark of Sweden (Demark ceded Norway to Sweden in 1814). The yacht's flag is from 1844.