There are so many easter eggs...
Most of them are in the "albums" section (if you click on one of the letters on the Greatest main page you are taken to a gallery of the albums, on both discs). I found the easiest way to find them is that if you click on each album one by one, and then click on available tracks, and then press up to the title at the top, if an arrow appears you`ve found yourself an easter egg. Also, for example if you play "Girls on Film" from this menu, you get a different version to the one if you were to play all the videos consecutively. Have fun investigating!