Rant ahead: If you're going to plan a night out, it's not that fucking hard to email everyone in the group what your plans are and let them plan on attending accordingly, rather than being all clique-y and asshole-y about it and saying "oh duh, sorry, didn't realize not everyone was cc'd on the last email", like an hour before you're planning on going out. I was already home and a 45-minute train ride away when I got the email for fuck's sake. At that point it basically feels like an un-vitation. Like, "we don't like you enough to tell you about this so you can actually plan on attending, we just sent out this mass email so people don't bitch about not being invited."
tl;dr my friends all suck at making plans and therefore fail at adulting.