I due volti del Generale Ombra

The film was almost complete fiction.

Use of reel to reel tape recorder. Whilst Americans may believe tape recording was a post-war development, it is a fact that Germany had built and developed practical tape recorders in the 1940's. They were used in both military and broadcasting situations. After the war, the Ampex corporation was given the German technology as a reward for their war work and they began to manufacture tape recorders in the US. The Ampex model 300 was a very close copy of the German production unit. Some industry journals even suggested that Ampex sold existing units seized from German warehouses before they began manufacture. However, the unit shown in the film is not an Ampex 300 and it is unlikely that German tape would be mounted on plastic reels as shown.

The credits read inspired by A.P. Scotland's "The London Cage". But in Scotland's own words "I had been a German officer... but that was from 1903 to 1907 during the Hottentot Wars in South Africa. True, also, I had secretly worked and successfully fooled the Germans and worked behind their lines... but that was alongside the Kaiser's Army in 1916." In WW1 & WW2 Scotland served as an intelligence officer interrogating captured German POW's. This culminated in his interrogating suspected war criminals at the end of the war.