The film draws from many of the real operations of 617 Squadron, in particular their attack on the German battleship "Tirpitz" in a Norwegian fjord, although that squadron used four-engined Avro Lancaster heavy bombers to carry the Barnes Wallis designed, 5.35-ton Tallboy earthquake bombs, not the twin-engined de Havilland Mosquitos depicted. However, the Mosquito was used by 618 Squadron in connection with another of Barnes Wallis' "bouncing bombs", called Highball. Though Highball was never used operationally, 618 Squadron was used as a special operations unit and is, probably, the closest match to "633".