Normally in the first Mortal Kombat when you get to the point where it says “FINISH HIM” on The Pit stage, uppercutting your opponent will send them into the spikes below. Sometimes however, and it seems kinda random whether or not it happens, if the killing blow happened to be an uppercut they just fall straight down, you don’t need to wait for “FINISH HIM” to show up.
If you happen to trade hits with your opponent when this happens, you retain control of your character while they’re falling into the spikes, something that is not supposed to happen. Raiden can take this opportunity to make 200% sure that his opponent is dead.
In the original Mortal Kombat, if you defeat the last opponent before Goro with Liu Kang, whiff Liu Kang’s fatality by performing it from fullscreen, and then keep walking forward, you can prevent Goro from appearing until you stop walking forward.
Once you let him appear he always does a long pose. You’re not supposed to have control of your character during this time, but in this situation you will, so you can easily let him fall down at about the 5-second mark and get a hit in as time expires to win the round.
In the original Mortal Kombat, when you throw an opponent into the right corner, you’re pushed out of the corner when they get back up.
If you’re fast enough, it’s possible to perform a Fatality the instant “FINISH HIM” appears onscreen, so that when you get pushed out of the corner you’re already in the middle of your Fatality animation. The end result is about as jank as you’d expect.