Mortal Kombat (SNES)
Whereas the original arcade version of Mortal Kombat was controversial due to all the blood and fatalities, the SNES port was controversial due to censoring said items per Nintendo policy. It also gave a huge edge to Sega, whose Genesis had a version that didn't censor at all and even had a blood toggle.
There is some unused music that is used in the original arcade version.
Using the Pro Action Replay code: 8084CBA9 8084CC07 allows you to access a buggy duplicate version of the Courtyard arena after one fight (as it follows the pattern of the Game Genie codes where you always fight in a particular stage after the first fight).
The game calls it the Throne Room on the Vs. Screen and plays Goro's theme on the stage as its BGM, it plays fine for a normal fight. However, trying to perform a fatality on this stage slows the game down immensely, then freezes for some bizarre reason.
Unused Initials Entry Screen
Game Genie code 676A-47AF enables an initials entry screen. While there is a high score table that shows up if you let the game go into demo mode, no initials entry screen pops up if you beat any of the scores.
The programming to display the initials entry screen is located at SNES address $98D361. A code block exists at $80836A-8083BF that can reach it. For some reason, this block is located during the Reptile battle intro (right after the "You have found me now prove yourself !!" text is displayed), and will execute if the 16-bit value at $7E0072 is <$8000. The $7E0072 address is set to $FFFF multiple times during the game, possibly as a way to disable the initials screen?
After entering the initials, the game is programmed to simply continue on to the Reptile battle.
Leftover Build Text
Some leftover build text, most likely related to the sound driver, starts at 0x0093C5 in the ROM:
leaves 3203 - 4979 for Module 12 leaves 699 - 391 for Module 13 leaves 5287 - bubbass1.bsn fltecho.bsn fltgit1.bsn fltgit1l.bsn fltgit1r.bsn fltgit1x.bsn fltgit1y.bsn fltgityl.bsn fltgityr.bsn gongf3.bsn hats.bsn prophet.bsn spinwd1.bsn ssnare1.bsn ssnare2.bsn surdrum.bsn surdruml.bsn
See if button combination & programming actually exists. Also, better video.
Pro Action Replay code 80D16AD1 enables an alternate super uppercut fatality for Johnny Cage. To perform it, press back while close to your opponent. This seems to be in line with his censored fatality in the Genesis version, but was cut in favor of putting his foot through the opponent's chest.