This is from the final version of the game. In 510, those spiked balls don't exist, and Sonic will not speed off when passing those red/white striped paths.

In the 510 version, both of the sides of this loop-de-loop are exactly identical. In the final the left sidehas been shortened, showing circular shape of the loop.

This is from the final game, you can see how it has been edited. Some additional Green box objects have also been added. There is also a beam a light crossing the level, there were not implemented in 510.

Most of the Stardust Speedway level is unifnishable without debug mode on. Reason being that the flip switch isn't in the game yet. In the final this allows you to go on two different plains of platforms, and get past other objects.

Here is Sonici in the final game. The flip-switch is in place, and Sonic can get behind it all. The pieces Sonic are behind are also different from 510, and some trumpets seen in 510 have been deleted.

In act 1, a light shines accross the screen once in a while, making the colours go crazy. This was probably a test of the lights flashing around, but a different method was used in the final.

In the far back of the level you can see a small Eggman head. This is not in the final game at all.

At the beginning of act 2 in 510 Sonic begins here. He is actually one platform higher than in the final game.

Here is where Sonic begins in the final game. You can also see with the image above that the background bit has been extended in the final.

Like a lot of the final levels in 510, all of the items are missing. Here is meant to be a life, spring, and a moving spike ball.

In the same section in the final game, all of those Trumpet and Cymbol pieces have been removed for unknown reasons.

Through the speedway in the final game there are these 3 blocks. These do not appear in 510, and because of the lack of springs, cause a very early death.

This platform is a bit of an oddity. In the final version it has completely changed, but looks like the original platform is hiding behind it.

Here is the final piece. You can still see the semi-circular shapes around it.

In the final game, the Goal post is moved to the left of Sonic, some of the Trumpets have been taken away, and the shape surrounding Sonic has been shortened.

Act 3 has the most drastic change of them all graphically. In 510 its more blue green in it's colour scheme.

In the final game the level has been drastically pinked up.

This is where you're meant to meet Eggman and Metal Sonic, but they're missing. Also, the background is quite different, with the two sections missing, both being those 3 blocks from previous screenshots.

This foreground object, looking like a street lamp, is not found in the 510 build.

Much like the beginning of the race, the final blocks are missing, and Amy is also not present, so you cannot finish the level in normally.

But above the structure is a horribly coloured capsule for Sonic to break. Sonic cannot reach it without Debug mode.

In the Bad Future of any of the acts there is lightning scorching the skies, as well as a flashing red/black backdrop. In the final both of these components were taken out.

These are the flowers for the game, both found in the bad future. The first one is from the 510 build, and the second from the final. They're obviously changed drastically over time.