If there's a hidden block directly above the player's head, it cannot be revealed. Examples of hidden blocks that can't be revealed are seen in levels such as Highwater Pass 2 and The Final Marathon.
Sections in maps where three or more blocks are stacked on top of each other will not load properly. The map data is correct, but the game gets confused when trying to read it. An example of this is seen in Under Skull Mountain 3.
Blocks cannot be stacked on top of ghost blocks because they get deleted when the ghost block reappears. An example of this is seen in The Crystal Crags 2 where the level designer's original intentions get ignored by the ghost blocks at the bottom of the map.
If you hit a shifting block or mushroom block into the path of an invisible block, the function of the invisible block will immediately be cancelled. When you move the shifting block out of the way and try to make the hidden block appear, it will no longer be there. A great example occurs in The Valley of Life
Blocks on top of spikes delete the gameplay function of the spikes (to hurt you). The spikes instead become mere art. An example of this can be seen in The Black Pit, where there is a section of hidden rock blocks in the same blocks as a spike pit. EyeClops can enlighten them, but even if he doesn't the pit can be crossed unhurt, since the game seems to only read the blocks, not the spikes anymore.
Fake steel swings will disappear at a certain point, once you walk some blocks to the right of their right end. As soon as only four blocks of the swing would remain visible, the whole swing becomes invisible, and it will reappear once you walk closer to it again. This does not happen on the left side of the swings.
A teleporter can be deactivated by pushing a row of two steel blocks right above it (thus preventing you from standing on the teleporter) or one space above, leaving a crawlspace in between. In the last case, you can still crawl on the teleporter, but it won't work anymore.
Some levels have rock or steel blocks in oddly positions, generally at the right bottom of the screen. Thanks to the K-E program, it's possible to look at what is below those blocks, which are a series of weird tiles, likely being typos when the level layout was coded. Examples include Madmaze Mountain, The Forbidden Tombs, The Cliffs of Illusion and Blizzard Mountain.
Dying or restarting round on the same frame a helmet is collected will cause you to respawn the level as that helmet, but with Kid's color palette.
Taking damage on the same frame a helmet is collected will result in that helmet having no effect.
If you collect or change helmets while steelswiped blocks are still travelling across the level, these blocks will disappear entirely from the level (only known way to "destroy" steel blocks).
If you change helmets as Micromax, and are positioned such that the top of your head will be in a block, the game will move you one block to the side instead of killing you. By doing this at the edge of a level (e.g. at the end of Pyramids of Peril where you switch to the Iron Knight) you can be pushed off the screen and out of the normal bound for the level.
The level's collision one space out of bounds is actually identical to that of the far left margin of the level, shifted one space up. Trying to go rightwards from here will severely lag the game and eventually crash the game.
Normally it is impossible for Skycutter to glide up or down slopes and there is no sprite for this case either. However, it is possible to get a gliding sprite when picking up the helmet directly on a slope, changing the character into an incorrectly-colored Kid sprite for a brief moment before Skycutter drops off the slope. The only location to observe this seems to be the bottom right corner of The Hills Have Eyes, where a hidden Prize block above a slope contains the helmet.
When charging a Robot in your Berzerker transformation. The robot dies, of course. But it also disappears instead of running around from left to right.
If a shooter block projectile hits a destroyed robot, it will mysteriously come back to life while still running at the same hyperactive speed, and also have 65,535 hit points.
Steel blocks pushed aside by Berzerker are supposed to disintegrate and kill enemies that happen to stand in the path. However, sometimes it happens, and sometimes not. This can especially be seen with the spheres in Elsewhere 5.
For no special reason, enemies (and sometimes even you) will occasionally not be affected by the projectiles of shooter blocks. This can often be seen with the tank in the flag room of Tunnels Beneath the Woods.
Some enemies like UFOs were erroneously programmed to appear in front of foreground tiles, causing them be visible as they pass through secret passageways.
Too many sounds playing simultaneously will severely lag or completely mess up all sounds played. This occurs when address 0036 in Z80 RAM is forced to process too many sounds at once. This can easily be heard in The Black Pit and Elsewhere 31.
If the above is severe enough, the game can crash. First, the Z80 processor crashes (evidenced by an eerie static death noise), followed by the whole game. The only effective way to avoid this is to pause and restart round immediately upon hearing this noise. The following is a list of all known places such a crash can occur (although most instances are pretty rare):
Hills of the Warrior 1 - triggering the giant shooter wall in the middle of the level.
Boomerang Bosses - crashes here are fairly frequent in two places when using speedrunning strategies. It should otherwise never happen during casual play.
Bagel Brothers - wedging yourself between the top head and the ceiling.
Elsewhere 19 - ramming against the rubber block wall at the end of the level, along with opening the 10-diamonds block while Skycutter.
Plethora - bouncing very low on rubber blocks during the boss's death sequence
The Wii Virtual Console and PS2 versions are known versions that will not crash in this manner. The WiiVC version can actually continue running without its Z80 RAM, while the PS2 version has no sound lag whatsoever.
If the game remains paused long enough, there will be no sound or music until the level restarts. This is a bug in the GEMS sound driver which Kid Chameleon uses.
Shifting blocks directly below another block make their moving sound when hit, even though they don't move.
Ducking directly after landing from a jump sometimes results in the wrong sprite set for the player character.
With Cyclone, if starting to spin at the same time as you bounce off an enemy, you will sometimes be shown as a while Cyclone helmet.
Attacking sufficiently fast, by using the fast attacking glitch (below), as Juggernaut, will replace the graphics of the skulls he fires with part of the Juggernaut sprite. This effect doesn't wear off until the stage ends, even when attacking normally.
During the game's ending sequence, each kid behind the grid wall falls after a randomly determined amount of time. In a rare instance, this duration is very long, and the VRAM will change while one kid is still visible. The result is a red checkered block falling instead of a kid.
You can always jump whenever a level starts, even if your starting position is in the air. Examples are Blue Lake Woods 1 and 2.
You can also always jump after a grab move with the Kid, even if the block you grabbed is gone. This is especially noticable with evanescent blocks.
Simply tapping the duck button and not holding left/right will instantly set your speed to 0, even while on ice!
Whenever you stop or start ducking, you are considered standing. Alternating standing ducking/standing quick enough while walking off a platform will make you walk on thin air. "Quick enough" is faster than humans can manage, so you will only see this with a autofire controller.
On platforms, ducking doesn't carry any speed or acceleration penalties compared to standing; on normal ground ducking has a much lower speed cap and acceleration.
Red Stealth usually cannot attack with his sword while jumping, but it is possible to attack enemies in the air by slashing first and then directly jumping. A bit into the jump, you will suddenly slash.
When you land from a jump, the counter to when you can attack next time is reset. This allows extremely fast attacking with Maniaxe, Red Stealth and Juggernaut in low corridors.
If you pause on the same frame you die with only one life left, the pause menu will appear after you fall off the screen. Hit "Give Up", and you will underflow the life counter, giving you 32,867 lives. This is known as the infinite lives glitch.
Due to the above glitch being an underflow, gaining a life will make your life counter read 0. Taking a telepad in this state will actually soft reset the game, unless you are playing in 2-player mode. In this mode, the game instead takes the destination coordinates of the telepad and spawns the other player at those coordinates in whatever level they are in.
A number of levels are problematic on some versions, and may be prone to occasional lockups. For instance, crashes are known to occur in the Final Marathon, but the source of the crash remains completely unknown.