Factual error: After escaping from Danzig, Grzegorz and Konrad flee to Warsaw, then to the eastern, Soviet-occupied part of Poland. They then make their way on foot right across occupied Poland and Germany to join British forces at Dunkirk, a distance of over 1,000 miles. Not a likely journey on foot at any time, let alone across hostile territory in the middle of a war.
Episode #1.7 - S1-E7
Visible crew/equipment: The Spitfire in the hanger has 1944 D Day markings in 1940. Also, this 4 prop Mark of spitfire wasn't available in 1940.
Factual error: Vernon is referred to as a squadron leader, but wears the rank insignia of the higher rank of wing commander.
Factual error: Tom joins the Royal Navy after the outbreak of war. He then mysteriously ends up on HMS Exeter during the Battle of the River Plate. In fact, Exeter was already in the South Atlantic at the outbreak of war and the battle occurred only three months later. There is no way that Tom could have completed training and ended up in the South Atlantic so quickly.
Factual error: Tom wears the trade badge of a naval airman. When he serves on board HMS Exeter he is working in the magazine, not with the aircraft. He then serves aboard HMS Keith, which carried no aircraft, at Dunkirk.
Factual error: Harry joins the army after the outbreak of war and is then a platoon commander with the British Expeditionary Force during the Battle of France. Actually, all the personnel of the BEF were pre-war regulars or territorials. The personnel who joined for the war were still in training.
Episode #1.7 - S1-E7
Factual error: Harry parachutes from a German Junkers 52, which the RAF did not fly. And if they did, the exit door on a Junkers 52 is on the left side, not the right which Harry parachutes from.