Documentary
To unlock the documentary, complete all 10 of the main missions. You can access the documentary in the special features section under options.

Audio commentary
To unlock the audio commentary, get at least a bronze medal in all 10 of the main missions. You can then access the audio commentary under the special features section under options.

Millenium Falcon
To unlock the Millenium Falcon, you have to earn a bronze medals on all 10 of the main missions.

Slave 1
To unlock Slave 1, earn a silver medals in all 10 main missions.

Ace mode
To unlock Ace Mode, you must earn a gold medals on every mission as well as beat the training missions.

Naboo Starfighter
To unlock the Naboo Starfighter, you must complete the Tatooine training in all four time settings. You must complete all objects, find all discovery items, as well as the two hidden bonus items in each zone. To set your Gamecube clock manually, hold down A when powering up. Choose morning (06:00), afternoon (14:00), evening (18:00), and night (23:00).

TIE fighter
To unlock the TIE fighter you must beat the Imperial Academy Heist mission in both the day and night. You can set your Gamecube clock manually as shown above.