In the Extras menu press RIGHT and a question mark will appear on the Wicker Man. Press ENTER and be subjected to 25 mins of fuzzy video and poor interview technique. It's An Extra Within An Extra.
On disc 2 highlight commentary on/off then press RIGHT. A small figure holding a torch will appear at the foot of the wicker man. Select this figure and you can view a 15 minute documentary on the recording of the audio commentary.
All easter eggs were generously submitted by Satelk