I can pass this guy...
Brian Parriot a BMW racer for San Jose BMW had a go off on his bike. He is ok, but the bike didn't fair so well.
My best guess as of what happen is the drive shaft has a connecting rod between the drive shaft from the engine and the final drive. If it's not htened correctly it can come loose and fall out. Disconnecting the drive shaft from the final drive.
Nate Kern had the same problem with another teams R1200S two years ago.