Insert the 1st disc. Go to the 'Director's Commentary' section, highlight the 'On' menu entry. Then press the 'Up' arrow key on your remote. This will play a footage about actor Arye Gross talk about his teeth, which are prepped in a weird monster-like manner.
Insert the 2nd disc. At the Main Menu go to the 'Deleted Scenes'. There highlight the 'Director's Commentary On' entry and then press the 'Up' arrow on your remote. This gives you access to a scene of Dean's female interest playing the violin. The funny part about it is how bad she is and how she accidentally 'spears' another band member with her bow.
Insert the 1st disc, from the main menu go to 'Scene Selections'. Once there highlight the 'Next' menu entry and then press the 'Up' key on your remote. This will give the change to view a footage of Henry and Dean doing a funny dance on the band stand.
All easter eggs were generously submitted by dachen