This item above Sonic in this screenshot is found in act 1 of the final version of the game. In 510 however, it doesn't appear at all. It grows and shrinks both horizontally and vertically, one after the other.

Instead of the morphing platform, these collapsing platforms cover the area. They will flip up and back continuously, much like the platforms from Scrap Brain Zone.

The Mekabu badnik has got a horrible palette problem. It's blue hide is black in 510, and it's grey saw is blue.

These slim, spiked platforms can be found in 510. They appear in twos, and sharply spring to one side, and then the other, impaling Sonic. These are replaced with empty spaces in the final.

In a slightly odd change, this one platform at the beginning of the level has the lights going in different directions. In 510 both lights go in the same direction in symmetry [bottom] while in the final the lights oppose each other.

These moving platforms have a large hole in them in 510, but in the final they're whole. Sonic is able to enter them, and he'll be squashed down into the platform, but not die. These were probably meant to work much like the rooms in the castles of Super Mario World.

The crawling badnik, like the Mekabu, has some palette issues. Oddly every one of them found in the level is holding a 1-up monitor. In the final if not hit carefully they'll grab Sonic and shoot him off from their behind.

The flowers are also different from 510 and the final. In the prototype it's more like a spotter sunflower.

Here in the prototype there is this line of collapsable platforms. Each platform can dissolve and will lead to a bottomless pit which will kill Sonic.

In the final game, this area is completely stable, with no pit of doom.

This Poubii robot usually swings only one mace, but in 510 an additional mini-mace has been added to it's abdomen.

These mace throwing balancers and floating in mid air, with a bottomless pit below. In the final a row of spikes are beneath it, and only one balancer is present.

These are the crumbling blocks from the prototype [left] and the final [right]. They're both quite different in appearance, one looking more like one block, while the other looking like two slimmer blocks.

In the beginning of Act 2 in 510, at a platform quite high in the level. In the final game the you begin at the very bottom of the level.

This is where you start in the final game from 510, but it still has very different surroundings. First of all there is a wall directly in front of Sonic, in the final it begings with an opening through some levitating blocks. You can also see an opening under the platform Sonic is standing on, which then goes to a whole new section of the level deleted from the final game.

Here is a comparison shot of where you begin in the final game. You'll also notice that the prototype has a slightly duller colour for the purples in the Past, and a lighter red for the safety cones.

In 510 there is also a 'roof' at the top of the level, seen here. In the final it's missing.

Act 2 has a very large amount of changed bits anc pieces in the landscape, particulary at the very beginning. This platform here entends all the way in 510 to get to a blocked path..

..but in the final it's completely dissapeared, instead fitted with revolving platforms similar to Scrap Brain Zone.

This section is blocked off bya diagonal piece of land. In the final it's been replaced with a straight platform.

Along with the large cogs in the level, which don't fully grip onto Sonic and make him flip off, there are also a lot of smaller cogs as well. These don't allow for Sonic to defy gravity either, and their design is much different to the cogs of the moving belts.

Like a few screenshots above, this platform has been replaced by a spinning platform in the final game.

The buttons in the levels are usually quite jumbled up. These are the two examples from the game, both work as they should.

The mechanism which makes you go into the background and foreground is missing in 510 in act 2, but is found in act 3, meaning the boss stages were completed first as they're the shortest.

The warp pipes have been implemented, but Sonic rides on the outside of them.

Here we see 3 springs, each moving left to right across this platform. In the final the item has a wheel at the bottom instead of just levitating, and this area only has 1 spring.

This piece of equiptment is missing from 510, it allows you to reach the end by jumping on one side at a time.

The shrink ray for Sonic has dissapeared. However Sonic can still run through the small spaces, he'll just get his head halfway through the wall.

Here Sonic is usually shot out froma warp tube, but in 510 there are some platforms to allow him to stop [left] while in the final Sonic'll fall to a lower platform [right]

This area is covered in. There is only one exit which you cannot get up to further left, but this area is very different from the final.

This is the same area in the final. The right has been covered up, and an opening has been made on the left.

These falling deathtrap platforms are not in the final, making it impossible without debug to reach the top.

The beginning of act 3 in 510, and it's very different to the final. In the final the platforms have been lowered, and background objects have been moved or removed.

This is the beginning for the final game. The Octagonal blocks in the background have been placed elsewhere, and oddly there is a small tree behind Sonic which would doesn't show it's roots like the ohers. A leftover?

The rotating platform is now present in act 3 of 510, but the iron curtains overlap it when it's not meant to.

You can enter the Eggman battle arena without defeating the Light Bulb enemy Gauntlet, but he won't appear until you defeat them all. Whenever they're about to strike the background will go dull and cause most objects to turn black.

In the Bad Future of 510 the top set of paralax scrolling is a horrible brown colour, in the final it's fixed to make the back look different to the front.

For comparison, here is an image from the final version. The backdrop objects have also changed colours to be more red/blue, not aqua/brown.