Alternate Costumes:
After the costumes are unlocked in the Krypt, highlight your chosen character and press Start at the character selection screen to access the new costume.
Random Select:
Player 1: Highlight Scorpion, then press UP+START.
Player 2: Highlight Sub-Zero, then press UP+START.
Walk On Air (Konquest mode):
In Orderrealm, go to the outermost walkway in H-5, and walk aginst the invisible wall.