I think you all missed two of the most common problems that lead to rescues: Loss of light (with no back-up light) and can't find the entrance once underground.
(Although one of my favorites is the group who just got tired of one member of their party so they just left him in the cave (Aug 2987 in Bowden Cave).)
Another problem is the long response times that occur between the time the accident occures and when the first rescuers reach the injured person. Even a short response time can be close to ten hours. As I recall, there was a non-caving mother who complained to this Discussion Board a few years back that the rescuers at a state park had taken an hour or so to reach her son after his accident. She felt that was a long response time.