Omega 13 option
Normally, the "Omega 13" option at the main menu will not be accessible until the entire movie has been viewed. To unlock it immediately, play the movie and skip to the last chapter. Return to the main menu to access the option.

Cast and crew interviews
Enter the biography screen, then highlight one of the pictures on the film at the top and press Enter.

Alien audio commentary
Change the audio settings to "Thermian Dolby 2.0".