On the stage Jack asks Peter, Paul, and Mary to come over to his house that night at 7 o'clock. They agree, and the scene changes to Jack's home. BUT there he says it is almost 7:30 and they should be here soon.
Jack asks Peter, Paul, And Mary to record his song and has them sing it in his living room. They do so, then say they can't record it for him (they tell him that it is not a folk song), then leave. Jack then lifts the piano bench and exposes a tape recorder, revealing that he has surreptitiously recorded the trio when they sang his song. BUT the tape recorder is NOT operating (both reels are stationary). Since it supposedly recorded the trio, then it should have still been on and recording when Jack lifted the piano bench. Jack should have had to have turned it off in order to stop the recording. Instead, Jack has to turn it on and plays what the trio just sang. Further, Jack does not even have to rewind it to play the trio singing it. It is already at the beginning when he plays it back.