Why does the CUS shot glitch in star fox 64 work? What error in the programming causes it?

In star fox 64 there is a glitch where if you shoot in front of, or in the general area of an enemy you will recieve bonus points, which count as a kill. Why does the this work? What is the error that occurs in the programming that allows this to happen?Why does the CUS shot glitch in star fox 64 work? What error in the programming causes it?its because in the programing they made the enemys matrix larger than the actual image of the enemy so even if you dont hit the enemy you hit the matrix which causes it to count as points