Someone told me he encountered a crash when he used Unicorn summon when there's an Unicorn trap casted by an enemy.
I then tried on pSX, pcsx-rr and epsxe and he tried on psp, the game all crashed right after the Unicorn command was chosen.
So I wonder whether this happens on a real playstation, though it is not a big deal to figure that out.
BTW, he who found this also tried the Japanese version, instead of a instance crash, the screen glitched and might crash if you use certain elements after that.