Dude, he used the warp whistle song from the original Zelda. It's found at 5:55, and repeats--somewhat broken up--all the way to the end. I think he borrowed the repetition from the OOT intro.
I totally agree that it has the same caliber as Zebesian Midnight. He's really outdone himself, even if the cameos at the end are a bit out of place. Just a little bit, though.
Funny Story: when I heard Frog's Theme, it took me by surprise and I started trying to figure out what game it was from (without cheating!!), so at first I thought of one of the newer Final Fantasies. But after 5 minutes I STILL couldn't figure it out, so I started beating my head on my desk (not really, lol) out of sheer frustration. Then I gave in a little bit and started to cheat by frantically searching my PC for the JUST the TITLE of the song has that little jingle in it. (I didn't want to listen to it. That takes all the fun out!) But then by some sheer stroke of luck (or through divine intervention) Frog's Theme started playing in Media Player about 5 seconds after I started looking. I didn't know whether to laugh or start crying. So I did both. Oh wait.... Was that out loud? Crap. . .
But I digress. They're at the END, so I can't complain too much. And besides, Vig is known for experimenting, after all. But anyway!
Here's a little trivia for everyone! Nintendo used the same sound for the warp whistle in SMB3.
You like me because I'm a scoundrel. You need more scoundrels in your life.