I felt a bit uncomfortable when sat near the back on a BA A321 at Heathrow one day. There was a problem with the jetty and it was announced that the rear door would be used for disembarkation.
There was a rush to the back of the, "I must be first off", brigade. The back of aircraft settled quite a few inches as the C of G shifted and the crew PA was to stay in your seat. Of course they did?