Unlimited Ammo:
During play, press Start and go to Options. Now highlight Button Config and press A. It will show you the controller of the Type A controls. While at this screen, highlight 'Aim', hold down the R button, and press Z, Z, Z, Z, Z, Z, Z, Z, Z, Z. The boxes will turn red.

Alternate Costumes:
Begin Leon or Claire's "A" game on either Normal or Hard. Head to the police station without picking up any items, in the alleyway near the opening where 2 zombies are waiting for you, go down the steps to find the zombie that holds the closet key. Once you acquire this key, go to the film room on the western side of the police department, and go to the lockers, this is where you will be able to change into different uniforms.

Play as Hunk:
Get an A ranking on two scenarios, one from each character.

Play as Tofu:
Get an A ranking on two scenarios, one from each character, and complete Hunk's scenario.

Extreme Battle Mode:
Get an A ranking on two scenarios, one from each character. It's found under 'Special Option.'

Rocket Launcher:
Beat the game (Leon or Claire's "A" game) in less than 2 1/2 hours, achieving an A or B rank.

Sub Machine Gun:
Beat the game (Leon or Claire's "B" game) in less than 3 hours, achieving an A or B rank.

Gatling Gun:
Beat the game (Leon or Claire's "B" game) in less than 2 1/2 hours, achieving an A or B rank.

The Secret Film:
This can be found in the S.T.A.R.S room located on the second floor on the west side where you find Chris's diary. All the way on the western side of the room, the last desk before the poster showing the S.T.A.R.S members, press the A button at the part of the desk that says "It's trashed... Someone must have searched the desk." Do it 50 times, and you will get the secret film.

Thanks to Revolution readers LsD_TriPpiN and Martin Brodeur!