What about Bob?

Revealing mistake: When Dr. Marvin is choking on his food Bob gives him the Heimlich maneuver. He then puts Dr. Marvin on the couch and jumps down on him. Dr. Marvin expels the food just before Bob knees him the third time. This is best viewed in slow-motion. We are lead to believe that the third knee drop caused the food to be dislodged when actually the food is spit out just a split second prior to Bob landing the knee drop.