I'm guessing this section is for users to point out things they've discovered which might not be getting generated realistically. You probably already know about everything that could possibly be noted, but just in case, here are a few observations:
1) sometimes streams flow uphill.
((photo removed from dropbox))
2) in places where the terrain is steep, trees often appear to float beside or slightly above the ground
((photo removed from dropbox))
(both of these shots were taken in the Andes)