A very interesting piece of alternate history. I'm not sure that Hitler had to even be in there for the story to be as good as it was. Of course including him, does draw you in.
I'm pretty sure it was important that it be Hitler. Right away, the author sets himself a challenge, to turn the most unlikely character into a Reluctant Hero. That's what he did with Edward Bear, and what Tolkien did by sending a pair of Hobbits into Morder. It's like a little game with the reader/listener, who then gets to see how well the author pulls it off (or doesn't). If it was a totally made-up character, it may as well have been in our universe of the Nazi Germany, and then it would be, well, boring.
As far as Charlie Chaplin goes, maybe it was something to do with the
Toothbrush Moustache that he and Hitler both wore: and maybe also his characters in
The Great Dictator, one of which is a parody of Hitler.
Concerning Hemingway, well, it seems like a
Moveable Feast sort of thing for him to be there. I did, however, keep expecting to hear that the title of the story he wanted Hitler to write was similar to "For Whom the Bell Tolls". Just as well that it didn't happen (at least not in the Escape Pod of our universe).
I love that the French become the new Nazi's. It goes to show the theory that any nations is susceptible to this kind of take over, I dont think the Germans are the only nation to ever fall into the trap. Blue-coat/Brown-shirt is a nice turn around.
Yeah, they just lost the war, and therefore the opportunity to write the history. For me, the so-called
headscarf ban in France came immediately to mind. Whatever the practical reasons for it may be, and never mind that it also applies to symbols of other religions, it still smacks of cultural imperialism. (As does Disney, but that's another rant.) "Common national values" and "for their own protection" vs "slippery slope" and all that.