I'm assuming they didn't get him after the war because he traveled through time.
Of course, the German leadership and The Hague would have to accept that something supernatural or magical happened.
Could they prove it was him?
I haven't seen the movie, but in the book nobody believes he is actually Hitler - everyone assumes he is an actor who just never steps out of character
Don't give me songs
Give me something to sing about
But, as some point he is going to get fingerprinted or a deep background check will be done on him. The more he interacts with people the more people are going to figure out that he is the real Hitler.
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What Would Jesus Do For A Klondike Bar (WWJDFAKB)?