While playing, use the second pad to input the following.

Effect	Code
Display enemy hit areas	R+B+Up+Start.
Free look mode (Use L&R to Zoom, A to move forward/backward, B to go up/down, C to tilt, X for fast forward/backward and Y for fast up/down)	R+C+Up+Start.
Freeze screen	R+Y+Up+Start.
Invulnerability	R+A+Up+Start.