The patent information is interesting:
http://www.google.com/patents?id=WfR...J&dq=3,145,797
If you find the patent a little dry, there is more information concerning the mechanics in the ABOUT section here:
http://www.me.berkeley.edu/one_wheel.../Biography.htm
It had gyroscopic steering
and stabilization, plus torque-reaction balancing. Maybe he leans a little bit in th film because he hadn't perfected the gyro stuff at that point. I do note the the Segway platform is low-slung. And guess what? The off road Segway model has bigger wheels than the regular one
Taylor made this thing to traverse mountain trails, where a large, single wheel would be beneficial.
All I know is, it would be really fun to drive one. Not as much worry about a face-plant compared to the Segway, unless the front platform snags a rock, LOL.