The trick for Reptile's fight required a ginormous amount of Guide Dang It! which involved not using the block button and performing a Fatality. The only moment in the match you're allowed to use the block button in order to trigger the secret battle is when performing Sonya's fatality, which requires it. The block button isn't a requirement for triggering this fight in the SNES version, however.
Kratos has different animations for when he falls victim to certain fatalities. While the other fighters react with fear, Kratos does not, a design decision which, according to Ed Boon, was requested by Sony Computer Entertainment as they didn't want to make him look weak. (He IS a Spartan after all.)
When killed by Johnny Cage's "And The Winner Is..." Fatality, Cage does not plant a faux-Oscar trophy into Kratos' split head.
In Mileena's "Be Mine" fatality, Mileena will not eat Kratos' head after tearing it off, instead going right to throwing it away.
When shrunk during Ermac's "Pest Control" fatality, rather than run around panicking, Kratos will instead challenge Ermac outright before being crushed (He's faced even bigger, after all.)
When hit with Cyber Sub-Zero's "Brain Freeze", Kratos will not fall down in a humourous rigor mortis pose.
When Stryker slams a grenade into Kratos' stomach during the former's "Have A Blast" fatality, Kratos does not panic before said grenade explodes, instead growling and trembling in fury.
When killed by Kung Lao's "Razor's Edge" fatality, Kratos does not wave his arms in horror when being dragged through the hat and being cut in two.
When hit by Noob Saibot's "As One" fatality, Kratos reacts to being bisected by a portal less so than other fighters do.
When ensnared by Skarlet's blood pillars during her "Make It Rain" fatality, Kratos attempts to break free of his restraints instead of panicking.
Kratos does not flinch when Kenshi throws his sword during the latter's "Split Ends" fatality.
Kratos does not inflate when being filled up by Rain's "Bubble Burst" fatality.
During Freddy's "Tell 'Em Freddy Sent Ya" Fatality, as soon as Freddy vanishes, Kratos prepares for a possible sneak attack instead of looking worried as others do. When tossed into the boiler in Freddy's "Welcome To My Nightmare" fatality, Kratos tries to grab at Freddy before the latter slams the door on his arm.
Kratos is one of the few characters that doesn't cry or get made fun of during his Babality.
Whenever Nightwolf or Kabal are playing in the Netherrealm stage, the hands try to catch them.
The head Kintaro destroys on his intro has its blood on his foot during the match. This doesn't appear in Story Mode for obvious reasons. And, if you skip the intro, Kintaro's foot will not be bloodied up.
Cyrax and Cyber Sub-Zero's winning round animations are different in Armless mode. In normal modes, they pop out a bomb from their chest, twist the top, and put it back. In Armless mode, the bomb drops out and explodes.
When Reptile wipes his mouth during his round win animation, the green liquid stays on his forearm.
When Sub-Zero's Bi-Han costume is selected, his voice set will change to Noob Saibot's voice set, only he sounds less... wraith-like.
If Johnny Cage wins the match, without having his sunglasses get battle-damaged, during his match-winning animation his glasses will break and be replaced by a new pair of shades anyway, but after Johnny says "Oh yeah." his shades will twinkle.
After Noob Saibot does his X-Ray, the vomit on his leg is kept for the remainder of the match. Also, when he uses his "Shadow" specials and "Saibot" specials, his real shadow disappears while the shadow-clone charges forward.
The characters being absent from stages where they'll appear, such as...
Goro in his Throne Room.
Noob Saibot and Rain in the Cathedral.
Shao Kahn in his arena. Likewise with Kitana and Skarlet not being chained.
Cyrax on the Desert stage.
Cyrax and Sektor's human alternates having different intros/outros, and the way they perform their special moves and fatalities is also changed. This actually plays into the competitive scene quite a bit, as some of the frame data between their human and cyborg forms are different and slightly influence their standings.
When teleporting using Raiden's Dark Raiden alternate costume, his teleporting is red instead of blue, but all his other powers are still colored blue.
When using Skarlet's Make It Rain Fatality on Sheeva, Skarlet will summon 6 blood pillars, to accommodate for Sheeva's 6 limbs (although this gets subverted otherwise as Sheeva's extra arms don't typically get special accommodation by the game, evident when using something like Cyrax's "Nothing but Net" fatality that dissects the opponent).
Kenshi's "Scatterbrained" Fatality usually gouges out one of the opponent's eyes, the one that is opposite of the direction he/she is facing. Doing it on the Cyborgs, Human Sektor, Ermac (Costume 1 only) or another Kenshi never gouges out an eye. Doing it on Kano, who has an Electronic Right Eye, only gouges out an eye if he's facing right.
Stages, such as Quan Chi's Fortress for Raiden vs. Johnny Cage, Kuatan Jungle for Mileena vs. Reptile, Outworld Marketplace for Johnny Cage vs. Kotal Khan, and Lin Kuei Temple for Sub-Zero vs. Revenant Sub-Zero, add new exchanges, or alter lines, to reflect their arenas.
If a character's intro animation has them interacting with something that changes between variations, the animation will take that into account. Examples include Kano (who puts his knife on his waist in Cybernetic) or Mileena (who leaves her mask down in Ravenous).
Choosing both Carl Weathers!Jax and Johnny Cage in the character selection screen will trigger an animation between them reenacting a scene from Predator.
One of Ermac's one-liners after a Brutality is "We are many. You are but one." Against the duo Ferra/Torr, it becomes "We are many. You are but two."
The intro sequences for Predator are rendered in infrared vision. Likewise, when choosing the "Hunter" variation (in which the Predator is unmasked), the color of the infrared vision changes, just as in the movies.
The infrared vision also displays Jason as no warmer than his surroundings.
If Predator performs a Brutality, he walks off the field toward the background. If he wins on the Kove, Krossroads, or the Pit (which would have him walking off the stage), he instead boards his cloaked ship.
If you perform the Skinned Alive Brutality, you do just that, unless you do it to an Alien. When you do that, the Predator takes the head and leaves the body behind.
Averted when the victim is Jax, who's flayed corpse is just like the rest of the male characters, even though his arms are supposed to be completely mechanical.
The newborn chestburster in the win screen for Alien changes depending on which race the victim was. If you beat Predator with Alien, a Predalien will erupt.
Going even further, one of Alien's brutalities involving a Face Hugger ends with a chestburster coming out of the opponent. If the victim had a hat (like Raiden or Erron Black) or some facial accessory (like Kano's eye or Johnny Cage's sunglasses), the Face Hugger will have it when it comes out.
Raiden's "Bug Eyes" Fatality involves shocking the opponent's head till both of his/her eyes pop out. The eyes popped out also depend on the variation the character is using. If used against Kano, who only has one eye, only one eye will pop out.
Predator's "Certain Death" Fatality, when done against another Predator in either of its masked variants, has the final shot not blowing the head in half, but instead just apparently causing a powerful impact to the head. Why? Because the masks are made for protection and it's obvious they are designed to resist their own weapons. The final shot of the match will even be different, since the Predator will fall forwards instead of backwards.
In Erron Black's X-Ray, the name written on the bullet he fires changes depending on who he faces.
Against both normal and Corrupted Shinnok, the bullet says "Shinnok".
In the event of a Mirror Match, the bullet simply states "Me".
Against a Predator, the bullet reads "Ugly Mofo".
If you hack the game to make him fight Baraka, Rain or Sindel, he has a bullet for them.
He even has a bullet for each variation of Triborg: Cyrax, Sektor and Smoke. Plus Cyber Sub-Zero, whose bullet is simply "Sub-Zero".
In keeping with the two previous games, some characters have differently-colored blood and this extends to their organs. D'vorah's blood (and therefore brain) is blue, for instance.
Zig-Zagged with Cyrax and Sektor, who always bleed black blood, but their organs are still red. Baraka's "Food for Thought" fatality and Skarlet's "Heart Condition" fatality stand out the most because of this.
X-ray shots in the game now account for Kano's faceplate rather than giving him a generic skull.
Like the "Scatterbrained" and "Bug Eyes" fatalities mentioned above, using Baraka's "Food for Thought" fatality on Kano shows only one eye on his skinless face.
Unlike with the Shokan in previous games, Kollector's extra arms are taken into account for any fatalities he falls victim to, causing them to be severed properly instead of being harmlessly phased through.note Fatalities were possible on Goro in MKX, and he - along with Kintaro and Shao Kahn - could be finished off with one in a hacked version of MK9.
In Chapter 8 of Story Mode, Past!Sonya is forced to fight in the Black Dragons' Fight Club, with Kano taking her gloves to "Make things fair". Sure enough, in the first two fights of the chapter Sonya is unable to use any moves that require her gloves. This also includes everything but the first hit of her Fatal Blow. Damn You, Muscle Memory! can also apply to both Sonya and the player since the animations still play out if you input the commands for those attacks.
Much like with the names on his bullets in X, one of Erron Black's intros in 11 has him pull out a wanted poster with his opponent's picture on them. The listed bounty varies between characters; the most notable are Cetrion (just shy of a billion dollars) and Johnny Cage ( a mere $500.)
All of the fighters from the first game (minus Johnny Cage), as well as Shao Kahn and Kotal Kahn, are worth five million dollars.
However, this is subverted for Noob Saibot and Kitana, who are both worth a million dollars. This is despite the fact that the former is the Sub-Zero from the first game (his brother is worth five million instead), and the latter became Outworld's new Kahn at the end of Chapter 7 of Story Mode, making her the only Kahn to not be worth five million.
Unlike the previous game, the pre-fight dialog avert this with the various skins, which almost always act as if their past self is saying them. This can lead to awkward situations such as Revenant Kung Lao denying that he's a revenant, Shao Kahn telling Dark Raiden that it's a shame that Dark Raiden is gone, and Cassie complementing her mother's killer.
Shang Tsung's post-brutality win pose has him transforming into the opponent and laughing. Hack the game to make him fight Cyrax, Sektor, or Kronika, and he will imitate their laughs, even though the first two are story only opponents and Kronika is normally immune to being a victim of a brutality.
If Kano is the victim of Johnny Cage's "Who Hired This Guy" fatality or a brutality (with multiple exceptions), the light on his Electronic Right Eye and chest will go out. Ditto for Cyrax and Sektor's visor.
If Cyrax, Sektor, or Kronika are the victim of Jade's "Bow Before Me" fatality, they will be bisected normally, as apposed to replacing the body parts with full body copies of themselves.
Kronika has a special line if she is the victim of Johnny Cage's "$500 Sunglasses" brutality. Since shes an Arcade boss you should not be able to use any brutality on her, she says Impossible!.
TheTerminator doesn't emote at all when fatalities are preformed on them, fitting as they are a machine. In addition, most fatalities that would reveal his organs shows that they are all machine parts.