After his apology, Johnny starts playing Sly and the Family Stone, and starts talking on the air over the song. When Andy enters Mr. Carlson's office to turn up the volume on the wall monitor so Carlson can hear Johnny's apology, Johnny is talking but there is no music playing.
When Johnny goes on the air to apologize, the on-air light turns on, then off before he starts talking, and comes back on again during the apology.
When Johnny goes back on the air to apologize, there is no one on the air. Les is doing a newscast, but with Johnny having finished his shift and Venus at the bar with Johnny, there is no disc jockey commanding the board.