On Disc 1 go to the special features menu and select "Reel Sound".
this is a text feature, but on each page a film poster will be highlighted when the page first loads, press "Enter" and you will see a clip from whatever film the text passage was talking about.
on Disc 2 press "left" from anywhere on the menu and a wall lamp will highlight, press "Enter" and you will see a short interview segment with "Moulin Rouge" director Baz Luhrmann.
Reviews: DVD Talk also has a review of
Singin in the Rain SE by DVD Savant.