In the bonus stage where you are riding a magic carpet with Aladdin and Jasmine, press the B button when the genie blinks to get a 1-Up or 2-Up.
To view the game's hidden ending, beat the game with 70 or more Red Gems.
To always reach the bonus round, stand on the open treasure chest and leap for the fluttering Scarab. Once the bonus round is accessed, wait until the Genie blinks while the wheel is spinning and tap any of the buttons. This will result in an extra life almost every time.
Here are the passwords for all of the levels. Input the following codes to gain access to the level next to the code:
Jafar, Abu, Jasmine, Genie - Level 2
Genie, Jafar, Aladdin, Abu - Level 3
Abu, Aladdin, Genie, Jasmine - Level 4
Jasmine, Jafar, Sultan, Jasmine - Level 5
Jafar, Jasmine, Aladdin, Jafar - Level 6
Aladdin, Jasmine, Abu, Sultan - Level 7
Genie, Abu, Aladdin, Sultan - Bonus Level
To access the level select mode, go to the options menu and press L, R, Start, Select, X, Y, A, B on controller 2, then exit the menu, then hold L+R and use the D-Pad on Controller 1. If done correctly, you will be taken to the level select mode.