One thing that made no sense to me with Nick threatning to blowup the dam
So he was pretty much telling Proctor John he was gonna blow the dam up regardless of whether he let his mom and sister go free, so why would he let them go free then?
Its not like Nick was saying he could have the dam and they'd leave, he was saying you don't let them go i blow the dam up, you let them go i still blow it up. So why would Proctor John let them go? Why no just say no if you're gonna blow it you'll have to do it with your family on it.