Its best to use this glitch when playing attack and defend on Calypso Casino, its also best to be the defenders (ensure you have motion sensors).

When starting the game respawn in the keno room, go out of this room and turn left, you should head past 2 elevators and end up next to some double doors.

Go through these and the room should have some escalators in it, don't go down these as they will take you to the vault - where the package is located (attack and defend).

Stay on the landing area and face to the right and head to the wall, at the base of the wall there should be a gold strip, try and get a motion sensor on this gold strip, this might take a couple of attempts.

Once in the right place the sensor's laser should go through the wall to the other side and will go through the elevators and even the keno room.

The motion sensor will sound when an enemy walks through the elevator and you will be aware of them and be able to kill them before they notice you.