Что-то вроде:
var time : float = 2;
function OnCollisionEnter(collision : Collision) {
for (var contact : ContactPoint in collision.contacts) {
Debug.DrawRay(contact.point, contact.normal, Color.white);
}
if (collision.gameObject.Tag == "Player")
Invoke ("DestroySelf", time );
}
function DestroySelf(){
Destroy (gameObject);
}