Sonic the Hedgehog 3 & Knuckles/Bugs

This is a list of bugs, glitches, etc. that have been found in the locked-on game Sonic 3 & Knuckles.

Some of these issues have been addressed in Tiddles’s fan-made ROM hack of S3&K entitled Sonic 3 Complete; this is noted where applicable.

General bugs

Mid-boss music for main boss fight

The game will occasionally play the mid boss music for the main boss.

Sonic can, thanks to Tails, lock the screen position and glitch through objects

If Sonic looks up and causes the screen to scroll, and Tails picks him up as the screen moves, the screen position will not reset once Tails stops flying; thus, Sonic can fall through objects below him once Tails drops.

Conversely, if Sonic crouches down and Tails picks him up after the screen scrolls down, Sonic can pass through objects on top of him.

Floating/zero-gravity Sonic

There are several circumstances in which Sonic can achieve a sort of ‘zero gravity’ mode whereby he can walk in the air, without fallling (as he should) until he jumps. He keeps walking at the angle of whichever platform he was on when the state was triggered and will not be able to walk at another angle without jumping again. With this mode, Sonic can sometimes pass through walls and reach areas that are normally unreachable without debug.

Circumstances where Sonic can achieve this state include:

• In Carnival Night Zone, if Tails puts Sonic into the cannon, Tails will enter the cannon whereas Sonic will not. If Sonic spindashes on the cannon and releases it at the right time, he’ll enter the zero-gravity state.
• In Ice Cap Zone, if Tails breaks an ice cube while Sonic is standing on it; and
• In Flying Battery zone, if Tails brings Sonic to one of the hangers.

Explanation: This glitch happens because the plus $08 flag at the RAM address $B02A (whose purpose is to stop Sonic from falling through objects) is not reset to normal after Sonic leaves the object on which he is standing. When Sonic stands on another object, destroys an enemy from above, or enters a bonus/special stage, the flag is properly reset to normal and the glitch thereby stops.

Move during end-of-level score tally

If a player times it right and jumps into Tails’ hands as he is flying at the end of the level, the player will still be able to move during the score tally.

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  Sonic can move during the score tally

Knuckles can hover in Hydrocity and Sandopolis

If you climb in Hydrocity Zone below one of those up and down moving rotating blocks, it will push you down without resetting you to normal status when you leave the wall, resulting you are climbing in the middle of nowhere. This video might explain it a little bit better.
The same thing can happen in Sandopolis Zone

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  Just climb below one of those up and down moving thingies and get pushed down

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  It can happen in Sandopolis, too!

Knuckles’s different versions have difference colours of skin and socks

(This may not be a bug per sé but is documented here for posterity.) The player character and non-player character versions of Knuckles use different colours, presumably due to palette limitations (of some type). This is most easily demonstrated by entering Sky Sanctuary Zone act 1 as Knuckles through debug mode. The two ‘versions’ of Knuckles have slightly different hues; the computer-controlled one is more pink than red. Also, Knuckles’s socks change colours depending on his role: when you are playing as Knuckles, they are green; whereas when you are playing as Sonic, Tails, or Sonic and Tails, they are yellow.

• DuelingKnuckles.png

  "Hey. You look sort of familiar, but...not"

Fan-made ROM hack Sonic 3 Complete now has optional IPS patches that allow the player to apply one or the other of these colours schemes to all versions of Knuckles, both playable and computer-controlled.

Glitches specific to Hyper Sonic

Hyper Sonic’s extraordinary abilities help to bring even more bugs and glitches into Sonic 3 & Knuckles. In particular, his double jump, which allows him to boost towards any of the eight main directions, can bring quite a lot of confusion to the mix.

Breaking scrolling for the Mushroom Hill Zone boss

By double jumping before the screen gets locked vertically, Hyper Sonic messes up the level’s scrolling. The level is still completable, though.

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  Note to self: do not jump this high

Escaping early in Flying Battery Zone

Hyper Sonic’s ability to cross small walls and barriers with a double jump allows him to escape from the force field in the pre-boss in Flying Battery 2. By doing this you can go almost all of the way up to the second battle with Robotnik. However, the cloud and object sprites are corrupted until Robotnik runs away as part of the first battle.

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  Hey Robotnik, where are you looking?

See the miniboss appear out of nowhere in Angel Island Zone

Peforming a double jump, as demonstrated above directly upwards during the Angel Island miniboss causes you to see the boss spawn and float down. This may be possible with a lightning shield.

Level-specific bugs

Mushroom Hill Zone

Act 2 boss sometimes shows as Dr. Robotnik rather than Eggrobo

Sometimes, Knuckles’s boss will have the face of Dr. Robotnik rather than Eggrobo as it should. This usually happens after the player loses a life, because it’s caused by the game’s not having sufficient time during reloading to patch-in Eggrobo’s face over Robotnik’s.

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  Knuckles fighting Robotnik in Mushroom Hill Zone

Not fixed in any version

This was fixed in the fan-made hack Sonic 3 Complete.

Flying Battery Zone

Knuckles fights Robotnik instead of Eggrobo

While playing as Knuckles in Flying Battery Zone’s second Act, the boss is Dr. Robotnik instead of Eggrobo. Unlike the above bug, this occurs every time.

This is likely to be due to the game’s artists missing this sprite. The battle's perspective is different – the Eggpod and therefore its pilot face the screen head on – and thus requires new sprites, which the artists did not implement for Eggrobo.

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  Knuckles fighting Robotnik in Flying Battery Zone

Not fixed in any version

The fan-made hack Sonic 3 Complete addressed this by implementing Eggrobo sprites edited from one of the ending cutscenes.)

Lava Reef Zone

Tails uses the wrong animation while falling with Knuckles’s boulder

When Knuckles throws the boulder at the end of the second act of Lava Reef Zone, Tails will use the wrong animation – facing sideways and rotating, rather than his ‘hurt’ sprite – if he’s not playing alongside Sonic.

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  Good

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  That’s no good

Exploding Iwamodoki shows 100 points but does not award them

The badnik Iwamodoki releases a small animal and displays a “100” points score when it explodes, but it does not award points to the player. Perhaps the lack of points – but, of course not the presence of the score notification – is intentional because the player cannot be directly responsible for destroying the badnik, which instead self-destructs when a character approaches. This might indicate that Iwamodoki was supposed to behave like Asteron, which upon self-destructing neither awards points, displays a notification, nor releases an animal.

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  Two Iwamodokis are preparing to explode, while the one at the bottom right has yet to progress to its exploding animation.

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  They all exploded, and even though they all displayed “100” points, note how the total score didn’t change.

Carnival Night Zone

Knuckles finds junk

While playing as Knuckles, one can take Sonic's path in Carnival Night 2, then glide over the boss area revealing a load of junk.

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  Knuckles looking at the wall right after he climbed the transportation tube up to Sonic's way to the boss

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  Knuckles at the top of the aforementioned wall

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  Knuckles flying to the right

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  Knuckles reached the junk, and there is even more below

Launch Base Zone

Sonic can fight Knuckles’s boss in Act 1

If Sonic passes through the set of spikes near the start and under a collapsing platform and a huge rotating cylinder, he will zip to the right and arrive at Knuckles’ boss arena. Two Twin Hammers will appear, but Sonic only needs to defeat 1 to proceed to the next level. However, Tails must lift Sonic to the ledge on top of the arena to avoid death when the next level loads. Sonic mustn’t defeat both bosses at the same time, or the game will crash. The undefeated Twin Hammer can be destroyed without worrying about the game crashing; otherwise, it will follow Sonic wherever he goes.

Failing to rotate on rotating floors

If the player’s character comes to a natural stop on the spinning floors after being rolled up into a ball, he will be using his standing sprite instead of the rotating sprites.

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  Sonic and Tails standing still on the rotating platform

Triggering the booster infinite times

If the player does a Spin Dash in the right place and at the right time, the character will trigger the booster for an infinite number of times, as long as he maintains his charge of the spin dash.

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  Sonic triggering the booster while spindashing