|Stopwatch item||An item box designed to stop time? Its use is unclear, however it may have assisted E-102's time-limited levels.|
|Chao emoticons||These would have appeared over the Chao's head but do not appear in normal gameplay. Found in AL_ICON.PRS.|
|Tornado life gauge graphics||The red "Tornado" life gauge is used in both Sky Chase Act 1 and Sky Chase Act 2. The Tornado 2 has its own blue gauge on the disc, but the graphics are never used. Found in ST_128S_HPGEJI.PVR.|
|Sonic Jam spring model||Sonic Adventure was built on the engine seen in the Sonic World section of Sonic Jam, but this is the only Sonic Jam asset to be found on the Dreamcast disc. The model itself is not seen in game, but the star texture curiously is - for switches.|
Found in TITLE.PRS, it appears a specifically-labelled "beta" version of Sonic Adventure existed at one point.
A build of Sonic Adventure was available to play at Tokyo Game Show '98 Autumn. Japanese instructions on how to play the game remain in most versions of the game.
Also found on the disc are six images which make up an older character select screen. Incidentally, "Choose Your Buddy" is also the name of the song used on the character selection screen. These screens were likely shown at the aforementioned Tokyo Game Show, but potentially other builds as well.
Found in C_SELECT1.PRS and C_SELECT2.PRS.
This prototype loading graphic is used in AutoDemo, but not in the final game. Found in LOADING.PRS.
Sonic Team took plenty of photos of the Sonic Adventure development process. This is the only one to be found in the game itself.
Through digging, several unused Tikal voice clips were found inside the game.
There are also several clips that can be found that discuss the Chao Gardens, some of which include information inconsistent with how the final game works ("Don't put more than six Chao in a garden" and its variations, for example).
One of the more curious absentees in Sonic Adventure is a giant two-headded dragon once set to appear in Sky Chase Act 2. It features in development screenshots and was briefly seen at the Tokyo International Forum unveiling, but is missing in the final game.
The object does exist (having originally been found in Sonic Adventure DX: Director's Cut (preview)), but the polygons are not linked up properly in the final build. The first image shows what was found, the second image shows how he should look when properly assembled, textured, and colored, and the third image shows how he looks in game in the Dreamcast version, placed by hacking the game's SET files.
The dragon continues to exist in Sonic Adventure DX.
The Dr. Eggman and Tikal objects used in cutscenes are actually programmed the same way as the playable characters, and can be played as with hacking. They both have only the most basic movement functions, walking and jumping. They can't hurt or get hurt by enemies and obstacles, and cannot run on wind paths and some loops.
Pressing the action button activates the free movement mode which is normally only active when debug is on. Dying before hitting a checkpoint or changing segments in an Action Stage causes the game to crash, as they do not have starting position lists.
Alternatively, when using a moon jump cheat code during a Tikal flashback, Tikal will jump as well.
A small hidden corridor can be accessed behind the door pictured in the above image. To reach it, the player needs to start a Spin Dash on the edge of the bridge facing it. At the bottom of the corridor the camera stops, so the player has to rely on the first person camera to look at the surrounding environment. At the end is a dead end where the player cannot return. If a glitch is used to get Knuckles into Sonic's Final Egg, Knuckles can also access this area if done correctly.
In the ceiling above this area and behind the striped object, Tails can fly to a unused corridor. When flying out, a strip of land will become visible. When Tails lands on it, he will go through the ceiling. This hidden part of the level seems to be fairly complete as there are monitors and rings.
Some textures used for E-105 are actually Dreamcasts.
This potentially provocative cowgirl billboard from Casinopolis is only used in the Japanese version of the game, being removed for unknown reasons in Western releases, Sonic Adventure International and Sonic Adventure DX.
Story Screen Scripts: