The Counterfeit Traitor

Movie (1962)
German title : Verrat auf Befehl
French title : Trahison sur commande

Starring:
William Holden (Eric Erickson)
Lilli Palmer (Frau Marianne Möllendorf)
Hugh Griffith (Collins)
Carl Raddatz (Otto Holtz)

Eric Erickson is an American-born Swedish oil executive who is pressured by Allied intelligence agents, led by British agent Collins, to spy for the Allies. He's quickly nearly crushed by the Allied requirements and the Gestapo which know his links with the British agents.

Junker Ju 52/3m

Most likely a Junker Ju 52/3m loan by the Swiss Air Force. Maybe the same airframe seen with three different registrations.
But such registration is anachronistic : D-with four numbers was superseeded by D-with four letters in 1934 and as the system never reach D-4000, only D-3050 was real (and really used for a Luft Hansa Junker Ju 52).