In the UK there are a number of pets go missing during the Halloween week because it is in the same period as bonfire night. It is not specifically related to Halloween. There are known to be groups of people/individuals, mainly teenagers, who do nasty things to cats (and animals in general) with fireworks for their own amusement. It is probably a good idea here in the UK to pretty well keep cats in for the two week period surrounding these dates, possibly longer.
It really annoys me that shops sell fireworks so early before November 5th as we have to be annoyed with them being let off right from mid-October through to the end of November. If you have pets this can be a frightening time. Most of these little corner shops will happily sell fireworks to minors.
Hail SATAN ...with bells on!
"Get thee behind me Satan".....proof christians like it up the ass!