Well, this is cute.
I would never have noticed it, but if you speed up certain sections of the Zelda: Breath of the Wild demo, you can hear one of the most iconic Zelda themes of all time.
How do people find these things?
The theme: Song of Time from Ocarina of Time. Very cool indeed.
Although you may remember Nintendo pulled a similar trick last time. If you reversed the Skyward Sword trailer there was a section where you could hear Zelda's Lullaby.
Seriously, man. Nintendo are pretty slick with the subliminals.