Taking a quick look, there's the haloing between the sky and the mountain in the right-hand side of the frame.
But what first caught my eye was strange balance of light on the beach compared to the sky. The beach is bright as day... as if the sun is shining directly upon it. Yet there is this very dark, dusky sunset sky in the background that couldn't possibly cast such bright light on the beach. The weird combination of bright, daylit beach and deep, dark clouds just struck me as sort of strange and unrealistic.
Just my two cents.