I see so many cards that say "Rescue 3" or "4" even "6" bystanders. When I play I never have more than 1-2 in play at a time. Surely this doesn't mean rescue bystanders that are NOT already in play; i.e. still in the bystander deck?
Yes it does. When you "rescue a bystander (or any number)" you rescue them from the bystander stack not from villains, as those are now "captured bystanders". I don't have access to the rulebook right now but it's very clear. But alas have no worry, you are not the first to make this mistake (myself included)!