I know the movie you're talking about, I watched it after I had read the book, naturally the book was much better. In the book they go into more detail as to how exactly the Nazis won and what exactly the Reich looked like... there might have been a map included.
But I suppose a fractured Germany map might be cool. It would suppose the Nazis won and at some point the Empire fell apart, maybe after Hitler's death. Honestly, I would think the map would look a lot like Europe does today, as without the Nazi overloads, many of the ethnic groups (presuming they would still exist) would push for independence and revolt, which would give us the map of Europe we have today. Or the Soviets would use the opportunity to strike from east of the Urals and conqur most of eastern Europe, giving us a Cold war map. Sure, there would be some geographical odds and ends which would be different, such, what would happen to Alsace-Lorraine or Austria.
Personally, I think a what if... Germany won map would be more interesting than a Fractured Germany map.
Here's the closest thing I could find to the map that I think was included in the book:
- Click image to enlarge.
I don't think the map would be as unique as we need for it to be made, but it might make a cool story.
And if you liked Fatherland, I highly recommend the book. And you should also check out Archangel, which is where Stalin sired a son to eventually take over and he kept him stashed up near Archangel. The son survives the collapse of the Soviet Union, and has murderous tendencies, much like dear old Dad. And eventually neo-communists try to use him to resurrect the USSR.