One way to deal with this is to ask at the beginning of an interview how much time there is for questions. Once you have an offer, you can also schedule extra interviews just for you to ask questions.
I'm sure it sucks for people with hire/fire authority to have to let somebody go early on when the decision to hire turns out to have been a bad one. But when it's the other way around, and an otherwise excellent new colleague regrets their end of the decision, the effect on morale is a lot more profound and widespread.
It takes some careful introspection and forethought to figure out what those crucial questions are. If they only come to you after the interview, send an email if you have to! But for Pete's sake, ask!