They should be the same for all of the characters.

Character slices open abdomen and bowels spill out.

and/or

taking a swan dive off of the pit levels.

Okay here are few
JohnnyCage: Pulls out a copy of MKA...
Kung Lao: Throws the hat in the ground and falls on it, or does a baseball slide into it.
Scorpion: Wraps his spear around his neck
Raiden: James Remar shows up...
Kitana: Whrist slit with fans.
Sindel: Flies up and falls down (yes I stole that)
Sub-Zero: Removes the amulet, and then suddenly freezes the ground into upward spikes, impaling himself
Sonya: Cinide pill
Kenshi: Uses his telekinesis to snap his neck.
Kano: 2 knife throat slit
Shang Tsung: Transforms into Martha Stewart, then he is killed in jail.
Knightwolf: Commands his axe to light up then he catches on fire too. TOASTY!
Frost: Creates a giant ice ball then drops it on herself.
Bo Rai Cho: Takes a sip, realizes its Bud Light, then starts to pretend a pink elephant is killing him, instead he is chocking himself
Baraka: Puts both hands to his head. SNIKT!
Millena: Looks in a mirror.
Smoke: Walks away walks up to a doctor. Doc tells him he has lung cancer and has no donors and that he will die -5 seconds ago. Doctor moves out of shot, see dead smoke, Doc says he should of stopped Smoking and then grabs his wallet and kicks him when he realizes he has no insurrance.

I got one for subby

He does a classic ground freeze from mk2. Then he backs up and runs at the ice on the floor. When he crosses the ice he slips and cracks his head on the ground......lol

Millena-pulls out a mirror and takes off here veil and screams in horror until her head explodes!!!

...i dunno, it was worth a try