Go down to the quantum level and physics becomes really weird. So weird that even Albert Einstein was stumped.The Physics is top notch. The only plot holes that I can find is black holes.
I mean, is the 1940s really necessary to the narrative?
Man, this really hit hardare you okay, boomer?
I think it's a good world building.
But there are characters that are very OP for their arcs and the author has to kill them in some way.
For example, dinosaurs, a meteorite that accidentally collided with the earth and that changed their ecosystems by starving them or by changes in temperature.
Another example was Rasputin who to die had to fall into a trap. But since he had resistance to almost all types of damage, they had to drown him in a river since he had no ability to breathe in the water. That is if we do not count that they were poisoned, stabbed and shot.
The other is Hitler who because of lack of troops could not defend himself and committed suicide. (I was waiting for a final battle against that soldier)
No magic.The earth has everything, you just need to bend it just a little to make it exciting. Which fantasy element isn't derived from the reality?