A condition has been identified in which the Segway PT can unexpectedly reverse the direction of the wheels which can cause a rider to fall. This can occur when the PT’s Speed Limiter tilts back the machine to slow it down and the rider goes off and then back onto the PT within a short period of time.
According to reports on the web, 23,500 Segway Personal Transporters are affected by the recall.
I don't know anyone who owns one of these devices, and was surprised to find that there are not one, but two dealers within five miles of my home.
qv: Segway: voluntary recall