Shao Kahn's Hara-Kiri. He throws his hammer up into the air, strikes his signature hands-on-hips pose, and waits for the hammer to come down, upon which it hits him on his head, causing it to explode. Then the body drops to the floor
Liu Kang's second fatality, when performed against himself or any of the female characters, can be absolutely hilarious.
The Kollector's Edition contains a trading card video for Johnny Cage. His enemies are listed as "Shang Tsung, Goro, Movie Critics".
In konquest, before an optional fight with Scorpion, a yes/no prompt pops up saying ""GET OVER HERE!!" Will you go over there?"