Married on the morrow (Live Lounge)
Location: Series 3 - Disc 2 (The Complete Box Set)
How to access: Go to the main menu, then select "Episode Selection" (not clikcing it). Press the "Up" button on your remote and a pink star is highlighted. Click it and you see a clip of Noel and Julian singing "Married on the morrow" on the Radio 1 Live Lounge.
Bollo playing the drums
Location: Series 3 - Disc 1 (The Complete Box Set)
How to access: Go to the main menu, then access the episode selection menu. Select the top episode and then press "down" on your remote and a blue cup is highlighted. Click it and watch a clip of Bollo playing the drums.
Location: Disc 7 - Bonus Material (The Complete Box Set)
How to access: It's not really an easteregg, since the DVD is like a giant easteregg itself with lots of things hidden in the menues. But there is another menu in list form hidden on the DVD, over which you can access all the material easily without searching through the whole DVD.
Navigate to the menu with three furry heads in front of the building. Select the right head (don't click it) and wait until the music had played through once. Then when it plays through the second time a small window in the building behind appears (on the top left corner). Click "left" on your remote until you can select the window. Click it and enter the list with all the bonus material. Enjoy!