connection to Germany (or even Austria) outside of The Sound of Music.  I suppose the producers might say it was used because it is easily recognizable in today's pop culture, and Von Trapp sings it in The Sound of Music movie as a sort of an anti-Anschluss / anti-Reich anthem.

That said, I liked the show a lot, but thought that the final season was just okay at best.  It seemed rushed and like they were just tying up loose ends as quickly as they could.  Also, the BCR was really shoehorned into the show and felt contrived to make the final product more palatable to a 2020 audience.  Based on their previous activities in Manchuria, Korea and elsewhere in the Pacific, I can't see the Japanese struggling to control the BCR.