I've only ever fallen off a horse once. The pony I was riding has a natural fear of bright things, particularly jumping poles. We were about go over a small jump (couldn't have been higher than 8 inches) and my pony stopped. I had to really kick it up hard to convince it that everything was okay and then the pony took a massive leap into the air and cantered away (we were only walking over the jump). I fell off a few strides after the jump and once I'd fallen the pony just stood there next to me as if nothing had happened.
At least it's another experience to reflect on.