The color pallet. Not that the colors don't match the countries, as that doesn't matter and I don't think that was why any of the colors were chosen. But that some of the colors are to similar to each other, especially against the ocean background.
In particular Kenya, Quebec, Pacific Russia, India, & some times Oz, when seen against the blue water, can be extremely difficult to differentiate.
Additionally, Near East's pale blue can be near impossible to distinguish with its two landlocked seas, and close proximity to the oceans.
I think a more vibrant color pallet could be more beneficial as, in general the more muted colors are the ones with problems. I don't know if it can be fixed, but I wanted to see if any one felt the same way.
P.S. While not as bad as the four green nations, the similarity between Ghana and USA is sometimes problematic.