This article contains a list of glitches from Shadow the Hedgehog. Unless otherwise noted, all glitch names are conjectural. Many of them have not been confirmed by Sega.
List of glitches
ARK wall jump glitch:
In any level aboard the ARK, the player can Homing Attack any wall near an automatic door, then wall jump towards the door. The door will open before the player can touch it and Shadow will perform an extra long wall jump.
To perform this glitch, the player should find a spotlight in Digital Circuit that points down into an abyss. In a very difficult to perform instance, if the player jumps into the abyss and the spotlight shines on them while Shadow says "Damn, not here!" he will fly back upwards, although a life will still be lost.
Protector of the ARK:
This glitch can only be performed in The Doom stage. When the player has healed 9 out of the 10 researchers for the Hero Mission, they should pick up a Heal Cannon and fill up the Hero gauge (preferably by putting out fires). When it is full, the player must rush over to the area with the researcher, fire the Heal Cannon at the researcher and perform Chaos Control at the same time. The level will be cleared, but the screen will stay white for an unusually long amount of time. Shadow will repeatedly say "Damn!" or "Damn! Not Here!" while also saying "I will protect the people of the ARK!" or similar.
In the segment of Space Gadget where Shadow must grind on a long-winded rail in order to reach the Chaos Emerald, if he manages to use Chaos Control there at the proper time, Shadow will fly forward as usual. Once he hits one of the boost rings, he will fly backward instead.
Right before the segment mentioned in the Reverse Flight glitch, Shadow will hit a gravity switch. Hold the control stick up and Shadow will not land on the rail, but will fall directly to the platform with the Emerald. If done correctly you can also get the secret key in the air.
In Central City on the Nintendo GameCube version, jumping at the right time when Black Doom says five will cause the game to crash.
This glitch can only be done in Lost Impact and also will not work on the Xbox version, since you need to control Maria as player 2. If Shadow sits in the Gun Lift and gets punched by Maria (or rather she punches the Lift), it will cause an explosion kicking Shadow out of it and making him lose rings. If done repeatedly, it can also cause the Lift to lock on acceleration, making it impossible to shoot Artificial Chaos.
Other turrets in other levels like Circus Park or Final Haunt can be destroyed as player 2, but will not cause the explosion.
"Too fast, Shadow!"
In The Doom, if Shadow activates the door switches from the locked side using the Satellite Gun, and then quickly runs in the reverse direction, he may fall through an unloaded portion of the Stage. Due to bottomless pits not loading at that time, Shadow will fall infinitely, thus forcing the player to restart.
This also works in Lava Shelter. If Shadow rides the first set of rails too quickly, he may fall into an unloaded portion of the Stage at the first checkpoint. Interestingly, the checkpoint platform is still loaded, so Shadow can avoid falling if he lands on it.
This glitch has only been known to work on the GameCube versions.
Air Fleet Dark Mission trick
In Air Fleet, it is possible to complete the Dark Mission with a time of 0:00. Due to time bonuses, this will result in 50,000 point bonus, resulting in an A rank.
A number of unused lines can be discovered using glitches and exploits.
In Lava Shelter, on rare occasions, if Shadow loses a life but has not activated any checkpoints, the Egg Monitor will appear as Shadow's partner at the beginning of the Stage. Because of this, a normally unused line can be heard from Eggman: "This lava flow will prevent anyone from sneaking into my base!" (note that there is an additional space within the dialogue after "sneaking").