This piqued my interest for obvious reasons... the map looks nice but there is no snow on the mountains which is clearly at odds with their own franchise films. Also the river at the bottom travels all the way up a ridge line and down the other side. A river police violation if ever I saw one. Its pretty but poor in accuracy.
Edit - oh yes I should have answered the question asked... You can get real 3D dem mountain data and use that to make maps with nice shading in it. Otherwise you just have to ensure that all your 2D source imagery has its light direction aligned else it looks very odd.
Yeah, definitely a couple river violations. There's a part in the south where a river breaks into branches or a delta before intersecting with another river... except most of the branches don't reach the second river. So, two weird violations, but all in all, its mountains are what really, really impressed me.