List of Mario Kart 8 glitches
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This is a list of glitches in the game Mario Kart 8.
NOTE: All names are conjectural unless otherwise stated.
Hit without Hitting
Shell Shard Glitch
In Mario Kart TV mode, if a character getting hit by a shell is played in reverse after the hit, the shards of the broken shell will still be there when it normally wouldn't be.
Spiny Shell Attacks Incorrect Racer
This glitch is most common in N64 Yoshi Valley where there are numerous multiple paths, but it can happen under specific circumstances in other courses such as Bone-Dry Dunes, Dolphin Shoals, etc. Occasionally when a Spiny Shell is deployed and the racers in at least first and second place are in a section where there road forks into two, the Spiny Shell may initially follow the racer in first place and then change its target to the one in second place or the highest place out of those in the other path. This is caused by some courses especially Yoshi Valley having the checkpoint markers that determine the place of the racers being inadequately calibrated with the other routes, as players can see by going down the old bridge path in while in first place, drop a few places while in the turn and then suddenly be back in first place once the paths join up again.
The Mobile Banana
To perform this glitch, the player should acquire a Banana and drive to the part in Dolphin Shoals where there are many Warp Pipes that generate wind. The player then needs to throw the banana at the correct angle to make it be blown away to a tilted part of the course. If the glitch is performed correctly, the Banana will move on its own.
Mii Texture Glitch
It is unknown how it happens, but sometimes when a Mii is selected the skin appears to be white with randomly colored lines. However, if a different Mii is selected, the Mii is reselected or the race begins the texture returns to normal.
Twisting Right Through the Kart Glitch
Sometimes, when players are hit with a Spiny Shell, and when they are upside-down in the air, touch a Green or Red shell, they will turn the kart over quickly and in the process, twist themselves. They will cross their hands over in an impossible position, and their head will twist to pass through the center of the kart. It is unknown if any shell combination would make this possible.
Bowser's Castle Floor Glitch
This glitch is uncommon. If the player gets caught in some way under the molten Bowser's hand, they will be pushed under the floor.
Breaking the Lap Counter
In N64 Rainbow Road, on the ramp where the player glides to the finish (before the Start line), with the use of a mushroom and a perfectly timed hop, the player can fall off the track next to the ramp and trick Lakitu into dropping them before the ramp, allowing exploration of N64 Rainbow Road backwards on the 1st lap. On the way back to the start line from anywhere in that area, the game counts the 2nd checkpoint as the 2nd lap, then the 3rd checkpoint (Start line) as the 3rd lap, essentially ending the course on the 2nd checkpoint. 
Cloudtop Cruise Music Glitch
If the player gets hit by a Red Shell or Blue Spiny Shell while gliding to the thundercloud area the music will temporarily stop, until the player reaches the platform.
Cloudtop Cruise Trick Glitch
Rarely, a trick can be done on one of the Boost Pads in the stormy area, but only when the pad is struck by lightning.
On a bike the player will need to go to a 90° edge that they can fall off of. They must then slowly reverse off of it until only half of the front wheel is hanging on the edge. The player must then drive forward. One of two things will happen. If the player did it from an edge with a low altitude, about a fourth of the character will end up inside the wall. If the player uses a mushroom and hops from this position, they can fly through the wall, which results in Lakitu picking the player up. If it is done from a high altitude, the player will immediately fall through the floor and wall. This can be used to access secret areas or other parts of a course. It is easiest to do with Yoshi on the Jet Bike with Monster wheels.
Fall Through the Ground
Glider Pad Trick Glitch
Very rarely, when doing a trick on a glider pad, the character does a boost pad or ramp trick instead of the glider pad one. This could happen on every course with glider pads, but it has been confirmed in Wii Moo Moo Meadows , DS Tick Tock Clock , N64 Royal Raceway, GBA Ribbon Road , and Electrodrome, though in Electrodrome, it is more common.
Invisible Ramp Glitch
Stuck Lakitu Glitch
In Sunshine Airport on the metal ramp just after the first airplane if the player backs up slowly and falls into an out of bounds area Lakitu picks them up, but gets stuck under the track. This glitch can happen on other courses, such as Rainbow Road.
Thwomp Collision Glitch
In Thwomp Ruins, sometimes when the player takes the middle pathway at the three-way part of the course if they bump into the Thwomp while gliding when they land on the platform below it they may fall through it and end up in the underwater part.
Tick Tock Clock Clock Hand Glitch
On the final clock the player can drive onto the lower of the two hands. The player should wait until the upper hand comes around. If their timing is perfect, they can drive on the upper hand while the car is still being displayed on the lower of the two hands. This can be done with any character.
Rarely, birds that appear on the course may appear submerged in the terrain. This does not stop them from flying away when approached. The glitch persists in replays.