Sonic the Hedgehog 3/Hidden content

3D Eiosian Balls

A spinning mass of red balls, placeable by debug mode with some ROM hacking. It can be moved with the second controller, and it seems to have no apparent purpose. It is, however, similar to the effect when you exit a special stage - perhaps it's related in some way?

Lost Eggman Object

An unused Eggman object discovered by Nemesis. It appears to be nothing more than Eggman flying away towards the horizon. Purpose is unknown.

Leftover Sonic 2 Menus

By setting the game's screen mode to $24, you can access the Sonic 2 options menu in Sonic 3! Either use the following patch code:

FFF600:2400

Or follow the instructions on SCHG How-to:Restore Sonic 2 Menus to Sonic 3.

Unused Surfboard Intro

This animation was found in the Sonic 3 ROM. It's part of an unused intro sequence, in which Sonic surfs onto Angel Island, rather than riding in on the Tornado. This savestate will allow you to see the full sequence in action (thanks to Nemesis).

8th Special Stage

In Sonic 3, there was an 8th Chaos Emerald accessible via a hidden cheat code. In Sonic 3 Alone, the emerald would be the same colour as the 7th Special Stage, grey. To access it, to go the level select, set the sound test selection to 07, and press A+Start on the "Special Stage 2" selection.

Here's a map of the special stage you need to complete in order to obtain it:

In Sonic 3 & Knuckles, using the same sound test selection, you could access the same Chaos Emerald Special Stage, except with the level colours slightly altered and a yellow emerald in the place of the grey one. Also in Sonic 3 & Knuckles was an 8th Super Emerald Special Stage, with a larger yellow Super Emerald at the end of it.

These emeralds have no special effect in-game, however, and do not appear on the end of special stage tally in any form other than a score increase.