I haven't been stuck on a ride, but back in the mid-70s I was in line for Space Mountain and we were in the building already. There was a stoppage and they had to turn on the lights. We got to see the whole track. It dispelled the mystery, but at the same time, it made me unafraid to ride it, as I realized it wasn't some crazy thing where I was about to get my head chopped off. Definitely back in the days before youtube and nightvision cameras.
We had been in line for quite awhile and no one said the ride was closed, so around 15 minutes later, or a half hour??? they turned the lights off and started rides again. We made it on after quite a wait.