Board Thread:Questions and Answers/@comment-172.12.205.50-20150108172142/@comment-25653892-20150110191501

Spazzing out like that is one possible effect of tilting a physical SM64 cartridge in a physical N64. Not all of the data can be updated from the console to the cartridge, and not all of the data can be transmitted from the cart to the system, which can cause either really funny results or save data corruption. Mario's animations are not activated correctly, so the game sometimes kinda makes him do… well, that. Project64 cheats can emulate this effect, causing Mario's animations not to updated, and – if I'm correct – putting Mario in a configuration close to his polygons' original locations and angles. So the effect is a toggleable emulated glitchy data cutoff hack, or the like.