 In level 4 ("Dark Woods of the Serpent"), once inside Ripper Valley,  go downstream from the waterfall. You can dive under where the river  runs under the rock ledge. When you emerge from the water the game  will say that you found a secret area, but there is more in this  area you should investigate. Head south and jump on the short wall  and youll see an "unordinary" rabbit, a chalice and a knights  helmet. This is a reference to Monty Python and the Holy Grail. If  you blow up the wall beyond the chalice, youll be rewarded with two  fortune cookies and some missiles as well.