the biggest mistake.

though the movie has quite a few errors,the biggest one actually came at the end: the mirror in the last scene had become a portal(by the power of the transcendental knife)and it acted as a gateway between two worlds and the mass can move through.
while fighting with the evil entity,Jai throws the cursed locket to the protagonist,and it successfully come across the portal and then he throws a piece of wood to the same direction but this time, instead of coming across the portal, which it was supposed to, it breaks it! the mirror.
i
It was also supposed to come across as the knife was still in contact with the mirror..