File:Super Mario 64 - Mario's Inner Bowels (E3 1996, Scrapped)

At E3 1996, certain esteemed gaming publications at the time got to report on an upcoming secret level entitled "Mario's Inner Bowels", although some magazines mistakenly refer to it as "Mario's Lower Pipes" (most likely confusing it with another scrapped course, "Pipe City".) This level is quite the anomaly, as it appears to take place inside of an anus, particularly Mario's anus - not the subject matter you'd expect from a family-friendly game.

This footage possibly originates from either an E3 B-Roll tape or footage taken by a magazine that had gotten a review copy. Rumors claim that said review footage belongs to Electronic Gaming Monthly, although this is entirely based in speculation, and the true owner of this footage is still a mystery.

Oddly, E3 1996 was only a month in advance of the game's Japanese release, meaning this secret level was scrapped extremely late into development. Not much is known aside from this footage and the few screencaps taken by magazine reporters.

Some rumors claim that this level still has remnants in the source code through lines of code referencing a 3d model file entitled "mario_Poop_1a", as discovered in the Nintendo Gigaleak from Summer of 2020, which also revealed an unused Luigi player model and voice clips, alongside other beta elements.