Secrets

Spread Proton Bombs
In ''Imperial Academy Heist'' steal the shuttle and go in the tunnel to your right to grab the tech upgrade.

Advanced Shields Upgrade
The Advanced Shields upgrade can be found in the first mission, Death Star Attack. After the cinema that leads into the second objective of the mission (killing the TIE fighters) continue going straight in the set path, only veer to the left a bit. Stay close to the planet surface and you'll find the rocket-shaped upgrade blended in with turrets and such.

Advanced Proton Torpedoes Upgrade
Right when you enter the second mission (Ison Corridor Ambush), dip down so you can see the piece of debris in front of you. It's hollowed out in the shape of a rectangle with the upgrade in the center.

NOTE: You must complete the mission after collecting the upgrade in order to keep it.

Targeting Computer Upgrade
In the ''Attack the Core'' level, fly inside the Death Star until you are near the central core...a short way before the large opening, there are some pipes near the lower right. Fly under them to get the Targetting Computer upgrade.

Advanced Concussion Missiles
The Advanced Concussion Missiles are in the tunnel across from the Spread Proton Bombs in ''Imperial Academy Heist.''

C-3PO, R2-D2, and their pod
In Tatooine Traning, you can find either C-3PO, R2-D2, or the escape pod they crashed in as a bonus item. You will only be able to find one of them each time you do the traning, so you will have to look around.
C3PO = Blow up Jabba's Palace and look on the ground.
R2D2 = Blow up the sandcrawler and look on the ground.
POD = Out in the desert. Look around for it.

Advanced Laser Cannon Upgrade
BATTLE OF HOTH: After the Rebellion's Shield Generator is destroyed by the AT-AT, the Laser Cannon upgrade will appear in it's place.

Cheat on the Beggar's Canyon race
Trying to get the Naboo fighter? Well here's the easiest way to beat the Beggar's Canyon race. When Biggs goes down path 1 go down it until it says path 1. Now carefully slow down and go down and left, then as carefully as you can turn around and go to the start, then go down path 2. You'll still get credit for doing race 1, just remember to go back and do race 2.

Doing the turn around can take some practice but it's a lot easier than doing race 1. Also remember to stay low. If you scrape the wall a little bit it's okay, just don't scrape it too much.

Homing Concussion Missile Upgrade
In the Raid on Bespin level, after you destroy the first ballon, watch for an Imperial Tanker and shoot it when it gets close to the gas platform. This should eliminate about half of the tanks, and you will see the upgrade on the platform. It is also possible to fly under the tanks without destroying them to get the upgrade if you use an A-wing.

Advanced Proton Bombs
In the Razor Rendevous level, fly to the far side of the Star Destroyer and wait for an Imperial Shuttle to appear, destroy it before it reaches the docking bay to make the upgrade appear in its place. This upgrade increases the power of the secondary weapon of the Y-wing.

Advanced Homing Proton Torpedoes Upgrade
In the Vengeance on Kothlis level, before the transport lands, fly through a small gap in the demolished Star Destroyers command deck to pick up the upgrade. This will allow you to lock on to a target with proton torpedoes.

Advanced Cluster Missile Upgrade
In the 4th mission (Prisons of the Maw) Bomb an environmental dome between the weapons storage building and the communication relays and the upgrade will appear in its place. This upgrade increases the destructive power of cluster missiles, which are a secondary weapon of the Tie Advanced and Slave 1 ships.

Homing Cluster Missile Upgrade
This is probably the hardest upgrade to get, because it is floating in the middle of nowhere and is hard to find. In the Battle of Endor level, fly over to the Star Destroyer on the left and fly in the area to the left and below of it. Look from a shimmering white dot over the planets atmosphere, and you will eventually find it. This upgrade makes the Slave 1 and Tie Advanced ships go from useless to extremely formidable.

Unlockables

Unlockables
Follow the methods below for the appropriate unlockable:

Passwords

Password Cheats
Enter these passwords at the passcode screen. For the codes with more than one part, enter the first part of the code and you will hear a beeping implying that you entered it incorrectly. Immediately enter the next portion of the code and you should get the correct R2-D2 beeping telling you it has been entered:

Glitches

Free life/resupply
When you get to a break in a mission, the split second before it is about to enter a cut-scene, crash/destroy your ship so that the cut-scene starts before the crash scene ends. When play resumes, your ship will be fully shielded, and you will not have lost a life in the process!

Codes

Skip the Hangar
Hold down both R and L buttons while selecting a mission to skip the Available Craft screen and the hangar. You will then play the mission in the default craft.