Basically, if you take the third teleporter on the bottom path in Scrap Brain Act 2 and have 50 rings, you'll take a different route which is basically a shortcut to the end of the level. Found out about this purely by accident.
That scrap brain teleporter is a strange one. Completely undocumented, Completely untelegraphed and the only example of if in the whole game. More of an easter egg I guess. I knew there was stuff up there because of debug mode back in the day but I only found out how once the internet came along! As for bosses, imo a good Sonic boss needs to have 2 ways to defeat it. A slow safe way with little risk to the player and a high risk way where you can wreck it quickly if you dare. Bosses that you know how to beat but slow is the only option turn into a slog and kill the momentum.
Tim Rogers once made fun of challenges you already knew you could complete, but would drag nevertheless, saying they should have an "I get it" button. He later brought the idea back on a video I can't remember about some boss in Mario, and it really highlights how the worst bosses feel like puzzles you solve multiple times, but identically each time, so tension dissipates the first time around. So I'm not even sure a good Sonic boss should have a safe way, broadly speaking. Sonic Advance 2 bosses are less unanimously praised than I thought, but I love how even doing them the slow way is tense. Since your jump efficacy in approaching Eggman or avoiding attacks changes according to the angle of the terrain, and that depends much less on you, allowing for your precision to always change and for every attack to be dangerous. And, theoretically, you can deplete the arena of rings, so if you're too safe for too long, you'll naturally die. So there should be this natural push to ty to hit the boss more times every cycle at your own peril. I really like how this boss does this part: Well, not the "feedback loop reducing safety" part, because dodging his projectiles is easy enough here, but how this boss can take anywhere from 8 to 2 cycles to beat depending on how greedy you want to get. If you hit Eggman too many times at once, you'll either clip through his exploded sprite and die or you'll touch the water instead of him and die. Now make Eggman shoot one more projectile than before every X cycles and you'll force the player to either become REALLY GOOD at dodging or grow a pair. And that'd be a perfect boss to me, incentivizing greed yet punishing too much of it, putting you in a permanently unstable situation you can't get out of if you don't behave differently.
Indeed, most of the Sonic 1 SMS bosses can be got rid of pretty quickly except amusingly, the very first one, which hovers a pixel higher than your maximum jump height the first time around, then drops slightly lower the second time around (even the guy that did the TAS couldn't get him on that first cycle, which is as close to definitive as we're gonna get). Labyrinth is pretty slow as well, hitting him when he pops up from the bottom is very difficult to do in 'normal' play, so 99% of people are going to wait. It still has normal risk reward when he shows up at the top though, in that you can hit him multiple times before he launches the torpedo or you can get him once and safely jump to the other side ahead of time.
