Note: All of these items can be seen in-game by using debug mode to fall outside the playing area of the special stage. It is easier to see them when advancing frame-by-frame by pausing and pressing C.
|"Zone" Icons||Although these icons are found in the object list for the special stages and their graphics exist in the ROM, they are unused in the final game and have no known function; when placed, they act like normal solid blocks. They are labeled Zones 1–6, suggesting that they may have warped Sonic to another Zone from within the special stage as a sort of shortcut, or they were likely to indicate which Special Stage the player was in or which stage they came from after reaching the signpost.|
|1-up Icon||Extra life icon for the special stages. It is listed in the manual for the game, but it never actually appears in any of the special stages. It is, however, fully functional, and can be placed in any special stage; when touched, Sonic gains an extra life and the icon disappears like a ring.|
|"W" Icon||An icon with the letter W on it. Its use is unknown, and it has no function when placed in-game. This block is solid.|
|Eggman monitor||Does nothing. Is likely intended to hurt the player, as it does in Sonic the Hedgehog 2 (16-bit)'s 2-player mode. To add a functional Eggman monitor in the game see the SCHG page on how to add it.|
|Goggles monitor||Does nothing. Had it been used, it would most likely have been accompanied by the unused goggle graphics and may have provided the ability to breathe underwater. To add a monitor which adds a goggle Monitor that uses the goggle sprites, use this SCHG page.|
|Static or blank monitor||Does nothing. This is found in various areas of Scrap Brain Zone that the player can not normally access, such as inside walls. It is possible to break one of them, however, by "digging" into the wall in a jump and popping it (the image of the monitor is a portion of the ‘zappers’).|
|"S" monitor||Does nothing. This monitor also appears in Sonic CD prototype 510, where it grants the player both extra speed and invincibility. That is most likely the intended function of the monitor here, as an issue of Computer & Video Games alludes to a powerup which grants extra speed and invincibility. This suggests that the "S" monitors were functional at that point in development. In the 2013 remake it can be placed and once destroyed you transform into Super Sonic regardless of how many Chaos Emeralds you have.|
|This sprite shows Sonic standing while gasping for air. This was presumably used in Labyrinth Zone.|
|This animation shows Sonic holding his breath while running. It is speculated that this was used during the countdown to signify that Sonic must find air as soon as possible.|
|This unused sliding sprite is similar to the one used in Sonic CD’s Wacky Workbench Zone.|
|As seen in a couple of prototype screenshots in magazines, after passing a signpost Sonic would jump up and do a victory pose. This was removed before the final version, possibly because its use was complicated by the addition of post-singpost giant rings, which cause Sonic to disappear.|
|These Spin Dash–esque sprites are present in the final ROM, but their use is unknown. Some theories are that they were used for a move similar to the Spin Dash or that they are animations for some sort of warp movement, perhaps through winding tunnels. It’s also possible that a teleporter like the one found in the 8-bit version of Scrap Brain Zone would have played the animation.|
|This set of sprites showing Sonic falling or shrinking are not used in the game, and their intended purpose is unknown. They might have been designed to simulate falling in the death animation, or for a speed tunnel that would extend into the background.|
|Green Hill Zone||The checkered ball seen on the Green Hill Zone Boss appears to have been originally used as a separate object in that zone, as magazine pictures have shown Sonic riding down hills on it. These can be seen in debug mode but not placed.|
|Green Hill Zone||The two faces pictured here are not in their original palette, but they appear to be earlier versions of the faces on the totem poles of Green Hill Zone.|
|Green Hill Zone||These unused tiles were found in Green Hill Zone’s tileset and appear similar to the areas used in the underground areas of Sonic the Hedgehog (8-bit)’s GHZ. These may have also been used for a cut underground area.|
|Marble Zone||These spikes are horizontal, rather than the vertical spikes used in the final Marble Zone, and are also slightly thinner. However, they can be placed and are fully functional.|
|Spring Yard Zone||This unused graphic can be found in the tileset for Spring Yard Zone. It is unused in the final game, and can be found in several prototype screenshots shown in magazine previews. The sign itself, here, clearly says, “Let’s Go.”|
|Spring Yard Zone/Labyrinth Zone/Scrap Brain Zone||An unused frame of the switch sprite. When bit 5 of a switch's subtype is set, it makes the object flash, using this sprite. In Labyrinth Zone, this sprite's data is partially overwritten by the cork sprite in VRAM. Marble Zone's switch has no equivalent sprite.|
|Labyrinth Zone & Scrap Brain Zone||This is a horizontal sprite of the Burrobot. Perhaps the Borrobot dug back into the ground after a certain amount of time?|
|Star Light Zone||These lights were found in Star Light Zone’s data but are not used.|
|Star Light Zone||The three machines shown were found in Star Light Zone’s dataset but are not used in the final game. They appear to have been background objects rather than obstacles.|
|Final Zone||The left image shows the back of Robotnik’s legs, which can’t be seen normally. The right image is what is normally seen.|
|Ending||Bumper that appears to be a rosebud with an incorrect palette. The ending level shares its debug item list with the Special Stage, so the bumper is usable in both.|
|Unknown||Unused section of grass which does not seem to match with any palette in the game.|
Many early previews of Sonic the Hedgehog showed the text “PRESS START BUTTON” on the Title screen. In the final version it does not show up due to an in-game bug, but the graphics can be found inside the ROM. It is also possible to get them to display in the Japanese version: this occurs after accessing the secret credits screen via a cheat code (in emulators, the region of the emulator must be set to Japan), or an easier way is to enter the Game Genie code AB3A-DADV. You can also fix this bug in a disassembly, using this guide or Esrael Sonic Editor II .Splats is a prototype badnik from Sonic the Hedgehog that was cut from the final game. However, Splats was used in a lot of merchandise (even the Sonic the Hedgehog Archie comic featured it), which may indicate that it was removed late in development.
The graphics were found hidden in the ROM. While the actual purpose of the goggles is unknown, it is speculated that they were meant to give Sonic the ability to breathe underwater. It is also possible they just illustrated that Sonic was underwater.
Each frame of the graphic fits together with one of Sonic’s poses. For example:
These graphics were found buried in the ROM. Their purpose is unknown, but it is speculated that they may be part of an alternate ending sequence, in which Eggman explodes in the background while Sonic runs across the ending level in victory.
Thought to be the original method of accessing the special stage, this warp effect activates when Sonic touches the area in which the object is placed. Sonic disappears as he runs into it, and a warping noise plays. Sonic then reappears a few seconds later, likely as a method of testing the object.
The swinging platforms of Green Hill Zone instead carry a wrecking ball when the highest bit of their subtype value is set. The object is fully functional, and can hurt Sonic. Technically, the swinging platforms of Marble Zone, Star Light Zone, and the swinging spikeball of Scrap Brain Zone are capable of doing this, too, but the wrecking ball graphics are not loaded, suggesting this feature was only intended for Green Hill Zone.
When using the level/act select PAR code FFFE10:???? and selecting the third act of Scrap Brain Zone by changing the question marks to 0502, you are actually taken to Final Zone. To actually reach the Scrap Brain 3 used in the game, you have to select the fourth act of Labyrinth Zone by changing the question marks to 0103. This means that technically, Scrap Brain Act 3 is another level of Labyrinth Zone. This is understandable as both levels share the same graphics, differing only in their palettes.
The level order that is used during gameplay is actually quite different from the order according to the level slots, which may represent the original order before it was amended. The level select in early revisions also arranges the levels in the intended order. Alternatively, a simple level select Pro Action Replay code (FFFE10:??00) can be used to verify this:
|Green Hill Zone||Green Hill Zone (00)|
|Marble Zone||Labyrinth Zone (01)|
|Spring Yard Zone||Marble Zone (02)|
|Labyrinth Zone||Star Light Zone (03)|
|Star Light Zone||Spring Yard Zone (04)|
|Scrap Brain Zone||Scrap Brain Zone (05)|
|Final Zone||Final Zone (05)|
Level slot 06 leads to the level used in the ending cutscene.
Commentary found in the Sonic Jam strategy guide also confirms that Labyrinth Zone was originally intended to be the second zone but was moved due to its difficulty relative to Green Hill Zone.
On the Sonic Team Presents screen, text showing the full names of key staff members and their roles in development is placed behind the Sonic Team Presents text. You cannot see this, however, because both the text and the background color are black. With a cheat code, however, the game will hide the Sonic Team Presents text and change the background color to white, showing the hidden credits. In either ROM, with the region set to Japan, press , , , , , , , , , , , ; you should hear a sound confirming this. Then, when the demo starts, hold + + + and either press or wait for the demo to end.
The Credits translated:
|Design|| Ooshima Naoto |
|Sound Produce||Nakamura Masato|
|Sound Program|| Kubota Hiroshi |
|Sonic the Hedgehog (16-bit)|