Unlockable - Costumes

Ashley Special 1 Beat the game once.
Ashley Special 2 Beat the Separate Way.

Leon Special 1 Beat the game once.
Leon Special 2 Beat the Separate Way.

Unlock Extra Weapons - All weapons are only available from the 2nd Round.

Chicago Typewriter (main game) Beat Separate Way once.
Chicago Typewriter (Separate Way) Clear Assignment Ada.

Handcannon Get 5 stars rank in all Mercenaries stages with every characters.

Infinite Rocket Launcher Beat the game once.

Matilda Beat the game once.

P.R.L. 412 Beat the game on Professional mode once.

Unlock Mercenaries Characters

Ada Clear Village stage with 4 or more stars rank.
HUNK Clear Military stage with 4 or more stars rank.
Krauser Clear Castle stage with 4 or more stars rank.
Wesker Clear Waterworld stage with 4 or more stars rank.

Unlockable Extras

Alternate Title Screen Beat the game once.
Assignment Ada Beat the game once.
Mecenaries Beat the game once.
Movie Browser Beat the game once.
Professional Mode Beat the game once on the Normal difficulty setting.
Separate Way Beat the game once.