The goggles... they do nothing (for breathing)
The game's coding contains a sprite and item box for goggles. Logic suggests that it was supposed to work in the Labyrinth zone to allow the player to breathe underwater. It was probably dropped because... it doesn't cover Sonic's mouth.
Think that's daft? Hedgehogs can actually swim - it was a mistaken presumption on the part of Yuji Naka that made Sonic have to walk through these underwater levels in the first place. Anyway... it makes much more sensefor Sonic to hunt out pockets of air... or air bubbles. And lo, a classic level was born.
But that wasn't the only thing that changed. This sprite (below)is even loaded into the VRAM, ready to be used while you're playing, but is never triggered in the final build. Maybe Sonic looks too anime-styled as he holds his breath?
Likewise, this alternative 'Bubble GET' animation is a little crude - the 'proper' one is clearly superior.
Fan remakes have put the old sprites back into the game (as well as allowing modern-day gamers to play pre-release, totally unfinished versions of the original levels), but it must be said this video is utterly fascinating as a glimpse of what might have been... (example lasts until the end of the act)
Note also the different background in the video - something else changed for the final version. Another old magazine scan shows this 'beta' background in place:
Above: The pre-release version (left) next to the final one (right). Note thedifferent crystals too
You can see the game's distinct art style in this unused background, but there are also old magazine screens that don't really look like the game at all. What do you make of these two pictures? Prototypes? Mock-ups?
Above: Sorry about the watermarks. But look at the welcome sign - there's nothing like that in Sonic 1
The trees and ground look the same, but Sonic doesn't. There is evidence to suggest that this was indeed a prototype version of Sonic 1, as this concept art looks almost exactly the same. Rocks in the foreground, mountains, clouds... and the 'CG' styled trees may look different on paper, but if ever a sprite was meant to look like flat-shaded polygons of 1990-era CG, it's the Green Hill Zone foliage.
Above: Concept art for a 'CG-styled stage'. Must've been incredibly exciting to design Sonic 1
The levels themselves were slightly different in pre-production versions. Even the level select screen of the finished game has levels in a different order, suggesting that the progression we know wasn't always that way. But what about this little lot? Spring Yard Zone was originally going to look more like a casino level, which does make the bumpers make a bit more sense (as much as hedgehog-bothering bumpers suspended in the sky can).
Above: The foreground is familiar, but look at that background! All stars and neon. Too busy, perhaps?
There's also an unused graphic in the game code that probably would have been used in the Sparkling Zone before it turned into the less glamourous Spring Yard:
Can't say we miss it... But more interesting is the graphics tile that's present in the 16-bit version of Green Hill Zone's level furniture:
Above: The 16-bit graphics tiles (left) look exactly like the underground graphics from the 8-bit game (right)
Meaning? The two versions were perhaps meant to be more similar than they turned out. But I'd guess that the presence of underground caves would mean the player would spend large chunks of timenot looking at that gorgeous parallax background. So it was left out... but never truly erased from the game's code.