Note: All gifs were made from the Sega CD version of MK. As per usual, my disclaimer of the gifs not accurately portraying the game's animation, speed or framerate apply here. The gifs have also had their color palette reduced to help out those with modems.
Super Uppercut
Heart Rip
Electrocution
Game Gear Version
(Kano is not in GG MK)
Game Gear Version
In the arcade, you could knock up to three heads off your opponent due to a bug in Johnny's fatality timer. You could also do other things, like knock two heads off, then punch the opponent in the nuts or even give them a shadow kick.
Notice how shitty the heart looks. Rather than use the arcade sprite, the idiots at Probe decided that a fake-ass, cartoony heart would better illustrate the gore of this fatality.
In the arcade, this fatality yielded so much more blood...and in MKT, when you use MK1 Rayden and do it, the geyser of blood that shoots out of their neck is unbelievably over the top(as much of that game is).
Cartwheel Uppercut
Toasty
Spine Tear
Game Gear Version
Game Gear Version
Game Gear Version
You'll notice that it doesn't get dark for Liu's fatality, sort of showing his status as a "good" guy in this first game. In the arcade, you could start the cartwheel all the way across the screen, then shoot two fireballs, then do the cartwheel again, inching closer until you finally hit the opponent.
You can actually flame people from behind, just like you could in the arcade with this early version of the "Toasty" fatality.
Sub-Zero's fatality is another shining example of the pure laziness of Probe Software. Rather than use the re-drawn head from the arcade, they opted to just use the already existing head from the in-game match.
(The Pit is not in GG MK)
This fatality was brought back in MK3, MK4/G and more recently, MK: DA. Every time it has been slightly different, but always amusing.
The heads on the spikes are actually Tobias and Boon. Also, the bottom of the Pit is where you'd fight Reptile assuming you knew how...