(Back on topic) Since we're on prototype information and related, those of you may not know about the prototype Super Mario Bros. 2. Anyways, the prototype cartrage was sold on eBay for $350, and here are the differences:
1. Lamps, no potions in this version.
2. The player starts with 19 (?!?) lives.
3. The story behind the Sub-Con is different.
4. The bonus chance/ending screen is different.
5. The dungeon music is different.
http://www.planetnintendo.com/thewarpzone/smb_music.mp3 < here is a sample of the old dungeon music. Notice that it sounds a lot like the underground theme for SMB3.
EDIT: I would also like to mention this:
https://www.kaejae-worx.com/gallery/albums/Super-Mario-World-Beta/smw2.jpg