The mountain blends too much with the background.
But a good solution.
Nice job!
Maybe make the mountain a bit darker gray?
Mr. Rex looks very handsome, though! 
Agreed with the overexposure. Turns out there were duplicated lights in on the same layer.
-deleted unnecessary lights
-changed the sky
-darken the mountain a little bit.
Hopefully it is better.
The sky looks amazing! Very colorful scene that hooks my eyes, nicely done!
Oh my goodness yes!! With your first render the sky and mountains were so light I couldn’t figure what that “helmet(?)” was, and what was wearing it. Now, however, I can plainly see the very top of one of the trees is in front of that area, and I realized it’s part of the mountain, so that area must be a cave!!
Needless to say, it all looks great now, though I think Rex needs some sharp teeth, as he looks like he’s roaring, and sharp teeth would fit his pose perfectly. 