"why was morpheus afraid of falling off of a truck? why didn't he just float like he did in the judo lessons -- plus -- a fall from a skyscraper wasn't real, remember? why they worried about an 8-foot drop onto an imaginary freeway?" well.. consider that the Keymaker was on top of the truck with an Agent that wanted to kill him before he killed Morpheus, Morpheus of course trying to stop him and the truck moving at what.. 60, 70 mph? falling off would have given the Agent time to kill the Keymaker before Morpheus could infact get back..