Kudos to Wildstang for making the recovery! They're lucky the trackball is fairly light relative to a 135lb. robot.
When the same thing happened to us last year at Silicon Valley with the bottom spider leg, we had worse luck – an alliance member tried to help us back up and inadvertently pushed us all the way over!
At least the only damage done was dislodging the camera and sending it skittering across the carpet.
Although actually, I wouldn't have minded nearly as much if we'd gotten the tipping on video, but unfortunately the memory card came out of the darn thing...