The dreaming mind can replicate any sensation. In the case of falling, we may not have fallen great distances, but all of us have at some point fallen short ones. The feeling of falling off a bicycle, the back of a couch etc when we were kids. There are several mechanisms in the nervous system that control the proprioceptive feel of balance, gravity, contact, and where we are in space. The dreaming mind can coordinate and project all of these into our experience.
