 Four of the De Havilland Mosquitos seen in this film were airworthy  and three could taxi on the ground. The same crash at Abindon  Airfield, U.K., shot from a different angle, was used with matte  painting (by Tommy Howard (IV) (qv)s Special Effects team) to  look like it was crashing in Norway. No shooting was done in Norway  in fact. For "Norway" scenes, the mountains of Scotland were pressed  into service.