Have we forgotten Uruguay randomly joining Argentina for no reason just a year after Doomsday? Also, Argentina was in the critical transition from the dictatorship: here all goes smoothly as if nothing happened. I like my Argentina wanks as much as anyone (and it also makes sense it would become an important country post-nuclear war) but come on.
But the worst thing about it is the flag:
NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO MY EYES HURT
There are also some weird things, like Greek refugees outright colonizing Libya and Egypt, and British refugees doing the same with South Africa. Unfortunate implications all around. And the random little monarchies that emerge in survivor states everywhere, particulary in the USA that has no history of monarchies at all. Some African nations collapse out of nothing. The USA just... dissolves itself. And so on.
I'm also very doubtful that the world (as in climate and ecology) would recover so easily. The nuclear winter has been questioned, but I'm convinced at least some years without summer will happen.
Don't get me wrong, I liked reading 1983 Doomsday a lot. But it's not realistic by any means.