My copy says 18A (Canadian release)

Does anybody know why the Canadian release bumped it up to that? Strikes me as odd as I don't remember anything particularly strong enough to earn that rating.

I'm only asking cause I've watched the first one with my two younger sisters (11 and 12) and just curious if I should rewatch it first. I don't remember any of these movies being too extreme at all, so I was surprised to see that.