Le diable fait le troisième

I don't have much to add besides what others have commented, except to support what was said previously, that the filming locations in post-WWII Germany and Austria are the most interesting features in this film. Views of Munich and Saltzburg give a clear picture of the extent of the devastation that resulted from bombing raids at the end of the war. But for me, what I found the most interesting was the last scenes filmed at Berchesgarten in the ruins of Hitler's Eagle's Lair where the head of the Neo-Nazi organization seeks refuge after being chased by Gene Kelly et-al. This is the only movie I recall that showed this location before it was eradicated.