(Not sure if this has been said before, but oh well)
A) How did the lions survive in the deserted wasteland without food after Scar died? It didn't turn back to normal overnight; and B) What happened to all the hyenas?
The hyenas are the only characters that didn't show up in any of the other movies. I'm thinking those two questions are related.
My theory is that Simba and his pride ate the hyenas. How else would they have been able to survive in that wasteland with barely any food that Scar had left behind?
Turns out that one hyena is more than enough for a lioness to survive for a week even, and there were thousands of hyenas.
Seeing as lions in this movie are capable of building cages (
http://pridelands.eu/hd/image5678.html), I wouldn't doubt the theory that the hyenas were eaten.
So yes, I think that they hyenas were eaten, as bad as it sounds. But to me, it seems likely, given the situation.