Sonic the Hedgehog 3 & Knuckles/Hidden content

From Sonic Retro

Back to: Sonic the Hedgehog 3 & Knuckles.

Level select

SK level select.png

While in Angel Island Zone, jump on to one of the swinging vines, then press Left Left Left Right Right Right Up Up Up. A Ring sound will confirm correct entry. Press Start, then A to return to the title screen. A new option, "Sound Test", will appear below "Competition". Select that option to go to the Level Select screen.

On the level select screen, pressing C will change a value displayed beneath Angel Island Zone's entry, determining the player's character. The values are:

Debug mode

Sonic3&K MD DebugMode.png

Enter the Level Select screen, then enter Mushroom Hill Zone. Grab onto a pulley system and press Left Left Left Right Right Right Up Up Up. A Ring sound will confirm correct entry. Press Start then A to return to the title screen. Enter the Level Select, then select a level and press A+Start to start the level with Debug Mode. During gameplay:

  • Press A to reverse gravity when in normal mode.
  • Press C+B to cycle through all mapping frames of the character when in normal mode.
  • Press B to toggle normal and debug mode.
    • Press A to advance forward through the debug object list.
    • Press A+C to advance backwards through the debug object list.
    • Press C to place the selected object at the current coordinates.
  • During pause press A to fade to black and restart from the SEGA screen.
  • During pause press and hold B to enable slow-motion (this proceeds at half-speed for as long as the B button is held down).
  • During pause press C to advance one frame.
  • Current coordinates are designated by the top line of hex digits in the HUD.
  • Viewport coordinates are designated by the bottom line of hex digits in the HUD.

Enabling debug mode will disable all restrictions on the level select, allowing the player to use characters normally forbidden from accessing certain levels.

Eighth Special Stages

Sonic3 MD SpecialStage 8 Start.png
SonicandKnuckles MD SpecialStage 8 Start.png

The eighth Special Stages from both Sonic the Hedgehog 3 and Sonic & Knuckles can be accessed in this game. First, enable debug mode (see above), then set the sound test to 07, and press A + Start on the "Special Stage 1" selection to get the eighth Special Stage from Sonic 3, or on the "Special Stage 2" selection to get the eighth Special Stage from Sonic & Knuckles.

Both Special Stages will award a yellow Chaos Emerald and Super Emerald respectively when cleared (whereas the eighth Chaos Emerald was gray in Sonic 3). These Emeralds have no special effect in-game, however, and do not appear on the Special Stage results tally in any form other than a score increase.

Note that setting the sound test to any other value between 00-06 will load their respective Special Stages.

Unused content


Placeable in edit mode

Art Description
Sonic3K MD Sprite Monitors.png
An "S" monitor. This transforms Sonic, Tails and Knuckles into Hyper Sonic, Super Tails and Hyper Knuckles respectively.
Sonic3 MD Sprite AIZ2BreakableWall.png
A breakable wall in Angel Island Zone Act 2, which can only be placed with debug mode and is destroyed with a Spin Dash on the ground. A similar object is used as a wall that is opened with a switch. Remains unused from Sonic 3 alone.
Sonic3 MD Sprite CNZButton.png
A button of unknown purpose. It can be placed in either Act of Carnival Night Zone via debug mode, but it doesn't appear to do anything. Remains unused from Sonic 3 alone.
Sonic3 MD Sprite CNZDebugRing.png
An unknown Ring-like object that appears to spawn slope collision when placed. It is placeable in Carnival Night Zone. Remains unused from Sonic 3 alone.
Sonic3 MD Sprite ICZBreakableBlock.png
A glowing block that can be placed in either Act of IceCap Zone via debug mode. Jumping on it destroys it like the ice blocks. Remains unused from Sonic 3 alone.
S&K MD Sprite LRZ2SteppingStone.png
A lava stepping stone for the second Act of Lava Reef Zone. Similar objects exist in Act 1, but this unique art for Act 2 is never seen.
A platform for the Glowing Spheres Bonus Stage.
"F" gumball, placeable in Glowing Spheres Bonus Stage. When collected it makes the same noise as a Bumper Ball, but it doesn't do anything.


Art Description
Some strange platform. It's not placed in any level, but the graphics fit perfectly in both acts of Launch Base Zone. It has no movement on its own when placed and needs specific PAR codes to be entered to do so. To enable it use the PAR code 1EFC52:1200 and it will replace the first ring monitor. From there enter FFF7E0:00FF to make it move down and FFF7E0:0000 to make it return to its original position. The object was found by shobiz, and posted about in
Sonic Retro
this thread



Audio Description
The Sonic 3 staff roll music still exists within the game and can be played in the Stage select/Sound test at sound ID 26. Of all the Sonic 3 tracks that were replaced by their Sonic & Knuckles counterparts, only this song wasn't replaced.
A "game clear" jingle for Sonic & Knuckles at sound ID 32. Though Sonic 3 used this ID for its own jingle played during the ending, it isn't used in Sonic 3 & Knuckles at all. A longer version of this jingle can be heard at the end of the credits medley.

Sound effects

Even when locked-on with Sonic 3, some sounds still go unused.

Audio Description
Sound ID 3A and 71. Shield sound leftover from Sonic the Hedgehog 2
Sound ID 40. An electric zap heard among the Shield sound effects. This sound would later be used for the Thunder Shield in Sonic Generations and Sonic Lost World, and for the Phantom Egg's barrier in Sonic Mania.
Sound ID 5A. Sounds like something revving up. This would later be used in Sonic 3D: Flickies' Island.
Sound ID 6B. Unknown, possibly unused; sounds like a higher-pitched version of the sound heard when hitting an R, Up or Down block in the Sonic 1 Special Stage.
Sound ID 6D. Sounds like a door closing.
Sound ID 7D. Sounds like mild rattling.
Sound ID 84. Sounds like something charging up. Only seems to be referenced in some Zone with a high level ID which is composed of garbage data.
Sound ID 85. Sounds like it would have been used in cooperation with sound 84.
Sound ID 8D. Unknown, possibly unused; a very quiet sound.
Sound ID 8E. Another electric rev-up sound.
Sound ID 99. A small "tick" sound.
Sound ID A1. A low-humming, unsettling sound. This sound effect is later used by the Hotaru Hi-Watt mini-boss in Sonic Mania.
Sound ID A5. Sounds like something rising or powering up?
Sound ID A6. Another dashing noise.
Sound ID B5. A leftover from Sonic 1 that was used for the breakable diamonds in the Special Stage.
Sound ID BC. Unused? Possible waterfall sound effect.
Sound ID C5. Sounds like it would be used in coordination with sound C4.
Sound ID D1. Possibly unused; another very faint sound that may sound like static.
Sound ID D6. Rumbling/electric sound?
Sound ID D8. Sounds like a screeching warning siren. Repeatedly pressing the C button when playing this sound in the Sound Test makes it play longer.
Sound ID DD-DF. All of these sounds are duplicates of DB (heard when running across water in Hydrocity Zone) and are likely placeholders.


Sonic the Hedgehog 3
Sonic3 title.png

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Hidden content (S3&K)
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Sonic & Knuckles
Sonic & Knuckles title.png

Main page (S3&K|KiS2|Blue Sphere)
Maps (S3&K)

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TV advertisements
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Hidden content (S3&K)
Bugs (S3&K)
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