Movie that used to come on tv a lot?

I can t think of the name of this movie about a little boy who meets a horror film producer and helps him rig up the movie theaters so that when the monster is about to grab someone on screen the chairs vibrate and scare the audience, and they re living under the threat of nuclear war the whole time, and at some point the boy and a little girl become trapped in a bomb shelter and think the bomb has been dropped.