The plans for the maps have prolly changed A LOT, because 1. This map hasn’t been updated since October (when it was first shown), 2. There’s a lot of suggestions for what we would like to see on the map on this post that Vetex created:
well that’s probably not going to be the case forever.
Note that we cannot see any bodies of water at all outside of the current playable area and the area vetex has hinted to be making next.
I suspect the same will be true for other similar things like mountains.
Vetex said on twitter that the map is not finalized. He has only completely finished planning the south eastern part of the map. That is why the only mountains and rivers are near the east peninsula.