But what exactly is this version? Does a legitimate ROM exist? And why are there dozens of files online claiming to be the "E3 Beta" that are actually something else entirely?

(dated approximately May 14, 1996) is essentially the retail version with minor detail differences, such as Mario's jumping voice lines and specific coin graphics. The Cutting Room Floor

Super Mario 64 E3 1996 Verified Download 【ULTIMATE】

But what exactly is this version? Does a legitimate ROM exist? And why are there dozens of files online claiming to be the "E3 Beta" that are actually something else entirely?

(dated approximately May 14, 1996) is essentially the retail version with minor detail differences, such as Mario's jumping voice lines and specific coin graphics. The Cutting Room Floor super mario 64 e3 1996 download