What is the secret area at the end of Lego The Hobbit, for the 3DS?

In the 3DS version of Lego The Hobbit, after completing the end, there is an area that is only unlockable only after getting (to the best of my memory) 375 gold blocks. Any idea what lies in that secret area? It suddenly came to my mind but I searched the web and I couldn't find anything. Thank you!

Solution 1:

Never mind, I actually just searched again and I found a video. It apparently plays a cutscene of the final part of The Hobbit: The Desolation of Smaug where

Smaug escapes from his gold encasing and Bilbo says "What have we done..."

It does not, however, include any gameplay for the third movie. Kinda disappointing to be honest.

Here is the video if anybody wants: Click me