In the root directory of all US copies is old file upload data, using an earlier version of the format the game usually creates: SONICADV_H00.BIN (Chao upload) and SONICADV_H04.BIN (World ranking). The Chao file contains a baby Chao called ♥BUDDY♥ that was submitted by segaeigh@concentric.net. It is 65% of its way towards evolving and comes equipped with rabbit parts.
The root of the 1998 Japanese version's disc houses files labelled PDATA10 through PDATA19. These appear to contain thousands of random Japanese commercial addresses belonging to various establishments, including but not limited to stadiums, hospitals, cemeteries, and even Capcom.
Due to their insane length, you can find these on the Data page.
The following text string is found in ADVERTISE.PRS. It is also loaded into RAM upon entering the menu:
Team Andromeda
This is part of unused code located in RAM at 8c906536 that writes menu voice enable files to the VMU. Normally, the voice files have to be downloaded, but this function will create all voice files on a certain VMU. There is no hidden or disabled trigger for this; the function is called from absolutely nowhere. Since it creates all of the files at once, and not just one, it likely was used during development to generate the DLC files that were placed online, and wasn't intended as an unlock system.
Team Andromeda was a development team at Sega from 1994-98 that was responsible for the Panzer Dragoon series. All menu voice files contain the same string. The game enables a voice file when a file with the correct filename exists on any VMU, and does not actually read the files, so this string is unused in the final game.
A number of the screenshots used in the game's credits for each story have subtle differences to what's seen in normal gameplay, suggesting that they were created using an older version of the game.
Sonic
The skybox is stretched - it's using the earlier sky's model and the final's texture.There are no dash panels here and the lighting is slightly darker.There's more debris flying around the stage and the objects below are missing.The lighting on Sonic is different and it's impossible to fill the vault that high with 264 rings.The scene where Eggman ambushes Sonic, but at a different time of day (notably, the same time of day used for Tails' version of this scene in the AutoDemo).Knuckles is in a slightly different spot. The lighting here also looks slightly different.Low detail Tornado model.The rollercoaster is never seen from this angle.Very early prerelease screenshot.Many different objects, including the star panel in the background.Different Lighting. Sonic's drop shadow is off-centered.Different Lighting.Different Lighting. A different object layout can also be seen in the background.
Tails
One of the falling spike balls is in a different spot.The same scene highlighted above where Eggman ambushes Tails, using the same time of day as in the AutoDemo.Tails is riding a different snowboard here. The lighting is also very different. The gates seen in Sand Hill are also present here.Slightly different lighting.Low-detail Tornado model, used in early builds of the game. This model is only present in the Sky Chase stages in the final, with cutscenes using a higher-fidelity model.There seems to be very little lighting here.Sonic looks odd in this screenshot. The lighting is also slightly different.Different lighting.A different skybox can be seen.Early prerelease screenshot using Sonic's layout.The scene after defeating the Egg Walker at a different time of day.
Knuckles
It's impossible to have the Fighting Gloves at this point in the game.Another prerelease screenshot being used in the credits.
Amy
The camera is further back than it is normally.Different lighting.Different lighting.Different lighting.Different lighting.Unknown. The closest to this is before Amy enters Eggman's base.Different lighting.
Gamma
Different lighting. Additional targets in the background are missing.Appears to be the cutscene where Gamma enters the Tikal flashback. He doesn't start in this map, though.The background is horribly glitched and the lighting is different.Different lighting.The arena for the fight with E-103 is bigger, similar to how it appears when playing as Sonic.
Big
Big's eyes don't move in this scene.Icecap has the lighting from Sonic's version here. This level is usually set at night as Big.Another Icecap screenshot.The scene where Big encounters Tails at a different time of day.Different lighting.Different lighting.Another shot of the scene where Big encounters Tails at a different time of day.
Super Sonic
Different lighting.Super Sonic is never seen from this angle.
