Is that Tails glitch in every release of Sonic 3? As in PAL and NTSC? I played Sonic 3 stand alone a lot as a kid and don’t remember that glitch at all.
Yes, all final Sonic 3 ROMs are 99.9% identical (only the country code changes). I remember it happening very soon after I got the game.
Sonic 3 clearly isn't a "prototype" or a "beta" or whatever other word you want to use. Calling it "rushed" isn't quite right either. The decision to split it into two games was not made lightly. A good bit of bugfixing also happens after the game was released; this was even so back then. It's very possible that if the game was never split in two and was instead somehow released "properly" when it was supposed to, we could have seen all of the glitches we know from S3A.
S3 is the definition of rushed imo, it's clearly cut short and I felt that back when I was 8 years old. Sure they planned to cut the game up but then only had like half a year to tidy up what they had.
IIRC a big reason the game had to be so heavily rushed was because early development time was wasted on 3D concepts that never went anywhere (which is where the title screen model is from).