I realize easier explain.add 2 lowest digits of score(tens and hundreds) at the beginning of the stage.(posted 9250 days ago)If it is 1 or 11,you will find lamp(open all boxes) 2 or 12,you will find boots (speed up for 17 seconds) 3 or 13,you will find fork(change all enemies into cake) 4 or 14,you will find timer(stop enemies for 8 seconds) 5 or 15,you will find flower(not killed for 34 seconds). 0,6-10,16 or more, sorry you can not find any special weapon.
for example you start the stage with 41320 points, you can find flower at this stage. If 41310 ,timer is yours and 41300,fork..