When on the Start Menu, press and hold all the shoulder buttons, then wiggle the L-analog stick until you hear Dante and Trish say, "Devil may Cry."
Use 2 Players:
While in Doppelganger style, hook up a controller in Port 2. Then hit Start while you're playing for the second player to use Dante's shadow! Using the same technique, in Mission 19, you may also control Vergil when you fight Arkham!
Red Orb Wellspring:
In Mission 9: Faded Memories, you can come across Secret Mission 5. It is located right when you enter the cave through the waterfall, go up into the hole in front of you and examine the 2 glowing red rocks on the ground. Its called Destoyer, basically you have to destroy everything in the alloted time. When you beat it the first time you get a Blue Orb Shard, but everytime you break something, it spits out Red Orbs for you. You can play Secret Missions over and over, and with this mission giving you 1,000-1,500 Red Orbs, every time you play, its a sure-fire and fast way to get everything you need.
Special Ending Sequence:
During the end credits, kill more than 100 enemies