Cheat Codes
Code - Effect
ADMINISTRATOR - Full access to the MIB database.
ALIENSEYEVIEW - High mode
BACKSTAGEPASS - All levels enabled.
HOTPEAS - View all movie clips.
MAGICPOCKETS - All weapons
MARRYMEALECKS - One shoot Game Over
MASTERCONTROL - Activates wireframe mode.
MENINBLURRR - Drunk mode
NICELITTLEEXTRA - Secret Level
ONESHOTSPLAT - One shot kill
R8HARD - Invulnerability
RUNSLIKETHEWIND - Double speed
TINTEDSPECS - Men in Black shades
UFO - Infinite ammo
Walk through doors
With the speed cheat enabled, strafe left or right towards the corresponding side of a door, and eventually (it makes the process easier to move the camera down while attempting this glitch) you should phase right through the door, enabling you to pass through locked areas not available under normal circumstances.
Weapon glitch
When you have multiple weapons in a level, fire one and immediately cycle to another weapon. If done correctly, your previous weapon will still be equipped but it will act as the new weapon you selected.