I was a passenger in a FR 738 some time back when the crew inadvertently selected what I believe to be RTO during the landing roll out. The sudden decelaration was enough to propel me into the seatback in front, I sustained a minor injury to my right hand while trying to save myself. Very unpleasant and no explanation from the flightdeck. Senior Cabin Crew was in the flightdeck during disembarkation asking WTF was going on..