SMB: Minus Mario

The "Minus World" is a neat little glitch that can be performed in the original Super Mario Bros. A fun trick, though it never made much sense. So why does the "Minus World" even exist in the first place? And why is it an infinite looping copy of world 7-2?

Turns out that jumping through the wall actually tricks the game into loading the wrong warp zone... But that's only part of the what's happening. Just stumbled upon this really interesting video that explains it all...

Why the Minus World Glitch Happens (8:38) by MagicScrumpy
https://www.youtube.com/watch?v=Hv_h_R3o9r8