Anachronisms: When William Killick boards his transportation plane to Greece the C-47 Dakota shows "D-Day stripes" (aka "Invasion stripes") on fuselage and left wing. Historically and consistent with the period setting of the story - the "Blitz" - this must have been in spring 1941. However, these markings were not in use before June 1944.
Continuity: When William Killick boards his transportation plane to Greece the C-47 Dakota shows (incorrectly) black and white "D-Day stripes" on fuselage and left wing. In the stock footage (probably ex-RCAF ZA947 operated by the "Battle of Britain Memorial Flight") used for the subsequent takeoff shot the C-47 has no markings at all neither on wings nor the fuselage's underbelly.