Haven't seen anyone else talk about this:
In Act III there is a hidden scene with Nella bathing in a waterfall. Funny how she doesn't take that wierd hat off :)

Makes me want to start the game again from scratch and try running around the maps with different characters...

edit: damn youtubed messed up the uplaod :( going to have to reup

edit 2:
http://www.youtube.com/watch?v=EZjMD4dqKB4&feature=youtu.be
Now it works :)

^^..played two times through it but didn't noticed it...or any other hiden scene.
Are there more of them?

No idea. I'm on my first playthrough. There has been a lot of love put into this game so it wouldn't surprise me if there was more hidden stuff. Then again, budget constraints, so if this is the only easter egg of its kind, that won't surprise me either.

Nella needs to be completly alone for this to trigger. If the rest of the party is within sight the cutscene wont play. And it only plays once - can't repeat it.

Well...please post it if you find more :)