Revealing mistake: Right before the witches burst through the roof of Max's house, after they retrieve the book, you can see the charge used to set off the explosion in the window just below where they exit.
Revealing mistake: As Mary flies toward the kids in the cemetery, the wires holding her are visible.
Chosen answer: Binx had accepted his fate of being a cat forever so instead, he decided to stop the candle from being lit. It was only near the end of the film that he saw the death of the witches broke his curse.
THGhost