This caution applies to all cats but especially all black ones. I've worked at rescues, shelters, adoption locations for over 20 years of my life and this is just a seasonal warning.
I've seen many a black cat go missing in the month leading up to Halloween, and turn up at a shelter or dumped outside somewhere afterward....not usually returned home.
This does tend to be more common in city locations where often people can't have pets (which is why they take them).
It's still baffling to me that people would do this at all, but just a friendly warning from one cat lover to all the others, keep an extra close watch on your kitty for the next few weeks and have a happy Halloween!