Besides the "Beck Time" egg posted already, I found three others!
1)The first on the DVD can be found by selecting the into the "Cast and Filmaker" menu Highlite "Christopher Walken as Hatcher" the left click to watch how the filmakers shot a scene where the Rock gets an axe hutrled at his head and stuck in a tree.
2) The next can be selected by going into "Bonus Material" menu and then selecting the "Cast and Filmakers" menu. Go to Director Peter Berg's name and left click to get a highlited flame. Push it to hear the Rock talking about how crazy a director Berg really is.
3) Get into the Audio set up menu. Highlite the "English Dolby 5.1 sound" choice (it's the first one) then push the UP button to highlite another frame. Push it to hear the Rock talk about the improvised "pee" scene he had with Sean William Scott