Many years ago I got stuck in one while pregnant in the old Great Southwest Life Building on Texas Ave. for about 2 hours. They got it moving again but it didn't stop all the way down level with the floor, so we had to be helped off by laying down and rolling off the opening down to the waiting arms of a couple of maintenance guys. I was mortified when they weren't sure if my belly would clear the opening!
After that I decided it was the stairs for me. However, since I worked on the 16th floor - that plan fell apart pretty quickly.
Since then - never had another incident. I still get a little nervous though if the doors don't open right away or the ride is super slow.