I also think it helps to appreciate the historical context: this game was a major milestone in the development of the 3D platformer genre. Some of the bugs or treacherous optimizations may look naive to us now, but there had been few if any opportunities to make those mistakes prior to Super Mario 64. And in spite of the glitches, the game managed to be a huge success and highly influential even outside the platformer genre.

This video does a wonderful job of illustrating how a handful of underlying issues can combine and manifest in so many different ways, and this was only the tip of the iceberg of 3D game physics glitches. And some of these issues are things games can still fall prey to today.

This is exactly it, thanks!

Thanks for that. I will go through the whole video later but that at least covered the basic premise.

Essentially, due to the technique used for collision detection, tiny gaps in the geometry causes collision system to treat parts of the scene as having very thin walls that stretch to the top of the play space. Depending on if Mario's quarter steps align with this little gap means that a collision can be made despite it not being visible. Also explains why they impact Mario sometimes and not others.

Like throwing a marble through a mesh fence but you cannot see the fence. Odds are you will make it through but it is essentially chance.

True. If he wanted to make it a proper phd thesis he'd use language to muddy the waters so no one could understand what he was saying.