Air-strike and Ion-cannon together
One way to make both air-strike and ion-cannon together with just one method, press Start to pause the game. Then press Right, Down, Left(2), Down, Right(2), Down, Left, X, Square, then press Triangle + Circle. Unpause the game and you will see both air-strike and ion-cannon together. -From: patrick @ cybertech.com.sg

View entire map
While the game is loading, hold R1 + R2 + L1 + L2 + Circle + Square. Keep the buttons pressed until the mission briefing begins. Now the entire battlefield will be displayed. Alternatively, pause the game and press Circle(3), Up, Circle, Square, R1, Circle(3).

Instant ion cannon
Pause the game and press Right, Down, Left(2), Down, Right(2), Down, Left, X, Square, Triangle.

Instant air strike
Pause the game and press Right, Down, Left(2), Down, Right(2), Down, Left, X, Square, Circle.

Instant nuclear strike
Pause the game and press Right, Down, Left(2), Down, Right(2), Down, Left, X, Up, X.

Unlimited money
Pause the game and press Right, Down(2), Left, L1, Left, Right, Down, Left for an additional $5000. Repeat this code as needed for unlimited money.

Bonus level
Enter "PATSUX" as a password on the GDI disc. Then, a bonus level with $10,000, extra tiberium, and tweleve commandos will begin.

Cover operations missions
Enter "COVERTOPS" as a password. This password may be enabled on either disc with different results.

Japanese narration
Enter "GODZILLA" as a password.

View FMV sequences
Enter "CINEMA" as a password, then wait until the FMV sequences appear.

View credits
Enter "JC" as a password.

Alternate introduction sequence
While the game loads, hold Select to view an alternate introduction featuring Kane and his acting career.

GDI mission passwords
2 - Estonia: IY2E4RGPK
3 - Latvia:VMNMUJFZP
4A - Poland: 1NXZDC3MK
4B - Poland: LHGHL19AI
4C - Belarus: LHY8GYVDS
5A - Germany: W1N457LJ4
5B - Ukraine: OXL3NYNNO
6 - Czech Republic: 1MVDCPIIM
7 - Czech Republic: OX3CS3D4G
8A - Austria: WMJ8FPOQH
8B - Slovakia: AAY1YZS9J
9 - Hungary: CSGUOJ7AQ
10A - Slovenia: Z6J3CUD9V
10B - Romania: W5741QXPJ
11 - Greece: PZBVQGKOK
12A - Albania: 0M86O28IO
12B - Bulgaria: LWO3SMF6F
13 - Yugoslavia: YM3XI0625
14 - Yugoslavia: WMJQ8C0HG
15A - Bosnia: GTJ2PV460
15B - Bosnia: 4QLR9NRLA
15C - Bosnia: C9RO0JST0

GDI Special Ops mission passwords
1: 8PHJTYIP1
2: SZ4VH22RY
3: 878FR0G1M