there is a bug where if you quickly make matches, you will be able to make two pieces move in a way that is impossible.
example:
R=red tile Y=yellow tile G=green tile P=purple tile O=orange tile
imagine you have this order in a row:
RYRPRGPOPP
if you switch the o and the p to make:
RYRPRGOPPP
as the game is processing the decision, you can then try to switch the r and the y:
YRRPRGOPPP
then, as the game finishes processing the o and p switch:
YRRPRGO
you can quickly attempt to switch the r and the p:
YRRRPGO
and half the time, it will work!:
YPGO