Stop me if you've heard this: Hitler, Hemingway, and Chaplin walk into a bar...
Oh, it's not a joke?
That was the point that really threw me out of the story, when these three famous people from our history just happen to meet at a bar and become the best of friends. I just couldn't look past it as anything but a plot device. Hitler as protagonist is an interesting idea, but that just really bugged me. I still listened to the rest though because I wanted to find out where it was leading.
And the reason for filling the cast with celebrities seems to me in this story to just be to avoid the trouble of actually fleshing out their characters. Everyone knows Hemingway, so you don't have to bother explaining any further. Hitler had to be Hitler for the story to convey the story it was trying to convey, but the other celebrities just didn't need to be there.
On that note, it didn't work for me to have history diverge so far back in the past when the story is supposed to be about an alt version of someone who lived long after the split. Sure, if you want to tell a story about this alternate time period, that's fine, but I just find it implausible that all these celebrities are still existent with the same names. Much more plausible is that this is not even genetically the same Adolf Hitler from our history, but just another guy with the same name. After all, presumably there were many other Hitlers in his family tree, and I don't think Adolf was all that uncommon of a name. But if you go with that interpretation, then the story loses all meaning, so that way of thinking isn't much fun either.
Ragtime was 100% correct about the female character being just a plot device to motivate Hitler and that bugged me. Especially when he HAPPENS to walk past a rape occurring and that rape HAPPENS to be the only woman he's talked to in recent history. the occasional stretch of implausibility is okay, but there was an implausability around every corner, it seemed, and it just struck me as lazy for the story to rely on them so heavily.
One little nitpick: I'm pretty sure that there was an inconsistency in the legend written on the photo. When I listened to it, I'm pretty sure the caption had one word different when his son read it then when he wrote it at the end of the story. I could be wrong, I don't really feel like listening again to verify, but if the inconsistency is there, it's a little strange, since it's also the title of the story.