On the second "Bonus Material" menu, highlight "Filmmaker and Cast Bios" and press your Down button. The graphic of Kyra's jewelry box should be highlighted. Press your Enter button and you will be taken to a fairly hilarious 90-second clip from writer / director M. Night Shyamalan's first horror movie, complete with introduction (which is actually longer than the clip itself).
To access the DTS track just go to the "Setup" section and choose languages.
All easter eggs were generously submitted by SirDonk