Cheat codes:
At the Mode Select screen, hold the left and right triggers and enter the following on the D-pad.

R,U,U,R,L,D,R,U	Dark Knight Mode
L,R,D,U,U,D,R,L	Infinite Combo Meter
U,R,U,L,D,L,D,R	Infinite Health
L,D,L,R,L,L,D,R	Every Reward
D,U,D,L,D,R,U,D	Every Upgrade