On disc four, select Production from the Main Menu. On the Production menu press Up to highlight an icon in the top right. Selecting it will play a short documentary.
Bonus Featurette
On disc eight, highlight Post Production and press Enter. Highlight More and press Enter. Highlight Back and press Down to highlight the warrior icon at the top of the screen. Press Enter to see the hidden featurette "Be Careful What You Wish For...".
Production Credits
On disc two, highlight Navigation Options and press Enter. Then enter the numbers 52579 (the U.S. theatrical release date for Alien, May 25, '79) to get the DVD production credits.
On disc four, highlight Navigation Options and press Enter. Then enter the numbers 71886 (the U.S. theatrical release date for Aliens, July 18, '86) to get the DVD production credits.
On disc six, highlight Navigation Options and press Enter. Then enter the numbers 52292 (the U.S. theatrical release date for Alien 3, May 22, '92) to get the DVD production credits.
On disc eight, highlight Navigation Options and press Enter. Then enter the numbers 112697 (the U.S. theatrical release date for Alien Resurrection, Novenber 26, '97) to get the DVD production credits.