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Interface:
Disc 2: If you leave the main menu up for 2 "transitions" I'll call them, in the third one, The Others will walk by.
Reported by: KJmon

Bonus Feature:
Disc 4: Go to set-up. Then to "register your disc". Then press left, causing a record to pop out of the stack. Click it, you'll get to see the full cover of the Geronimo Jackson "Magna Carta" album. Click it, and you'll get a short clip detailing their history. (Thanks to SirStack). Right! Sorry. The video clip on the Geronimo Jackson doesn't seem to work on regular players, does it? Perhaps pressing some of the numbers on your remote will access it (since that always works for Simpsons' easter eggs). But the easy way is to use it on your computer in a DVD-Rom, and click on the bottom right of the album cover. A minute and a half featurette follows.
Reported by: KJmon

Bonus Feature:
Disc 7: Main page: there is a button above Phase 3 - it shows some info about the Dharma cookies.
Reported by: KJmon

Bonus Feature:
Disc 7: Phase 1: there is a button under Fire + Water next to Anatomy of an Episode - Dominic tells the Snowman joke.
Reported by: KJmon

Bonus Feature:
Disc 7: Phase 1: In 'Lost: On Location' Hit left twice on 'Everybody Hates Hugo' It's all about sweat (Thanks to Jamescush).
Reported by: KJmon

Interview:
Disc 7: Phase 1: 'S.O.S.' Hit left twice and the up. Sam Anderson hates heights.(Thanks to Jamescush).
Reported by: KJmon

Interview:
Disc 7: Phase 2: there is a button to the right of Return - An interview with Evangeline.
Reported by: KJmon

Behind the Scenes:
Disc 7: Phase 2: in Deleted Scenes, there is a button to the right of Seeing Walt - shows Malcolm getting wet for a Shannon vision.
Reported by: KJmon

Production Art:
Disc 7: Phase 3: there is a button to the right of Secrets from the Hatch - Shows a still photo of the mural painting in the hatch.
Reported by: KJmon

Interview:
On disc 7 there is a button to the right of the return selection in the phase 2 menu it starts a short interview called "On The Beach With EVI"
Reported by: Ben Williamson

Outtakes:
Best Buy Bonus Disc: From scissors press left to go up to Good With Kids, press left again and then down to reveal a button on the other side of Scissors. See a Jack blooper.
Reported by: CL

Deleted Scene:
Best Buy Bonus Disc: From What Kate Did hit left twice to reveal a button. It's a deleted scene between Hurley and Rose.
Reported by: CL