The Dev Team Thinks Of Everything: Mortal Kombat 9
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 instead attempts to break free of his restrains 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 instead 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.
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.
Cyber Sub-Zero's winning round animation is different in Armless mode. In normal modes, he pops out a bomb from his chest, twists the top, and puts it back. In Armless mode, the bomb drops out and explodes.
After winning a match in the Courtyard, the monks witnessing the fight gives a round of applause.
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.
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.
The internal models of the characters being different between characters (noticeable mostly in the X-Ray moves) in details such as:
Bleeding red, except Reptile who bleeds green, the Cyborgs bleeding oil and Noob Saibot bleeding black.
The teeth, with the Tarkatans having tons of sharped teeth and the rest having normal teeth.
If you start losing or spamming moves in Kahn's Coliseum, the crowd throws garbage at you.
Cyrax and Sektor's human alternates having different intros/outros.
The Secret fighters in Arcade Mode having no meter bar.
Subverted with the Story Mode intro, which shows the aftermath of Mortal Kombat Armageddon with everyone wearing their "new" costumes instead of their older ones.
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 accomodate 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).