Unlock Extra Difficulty
The Elite difficulty is unlocked after beating the main storyline once. This mode makes enemies even tougher than the Hard difficulty and only gives you your OCP Pistol and a knife, no SMG.
Level Select
With this option you can select the level you want to repeat.
Unlock 3 Different Endings
The ending is determined on what you do at the end of JBA HQ part 2. The only difference between the three endings is a quick 30 second news clip before the credits.
Bad Ending - If you didnt defuse any of the bombs at the JBA HQ.
Good Ending - If you managed to defuse both bombs at the JBA HQ.
Normal Ending - If you managed to defuse only one bomb at the JBA HQ.