I've... noticed... something odd.
Apparently, the main menu screen for Brawl... was... supposed to be... a playable stage...
The numbers are the numbers assigned to the stage. I can give a full set of stage numbers if you want, but asides from that, at number 100 I found that the main Brawl menu screen was assigned to it. I don't know what all this means, so if someone can translate it, I'd be glad.
Oh, and I can't wait for the US rips. I do hope these contents are still on the disk.
EDIT: Of course, this could also be the placeholder for the WiFi training stage or any other stage.