Trivia: Neither Nichelle Nichols nor Walter Koenig appear in this episode.
Trivia: The events and description of the Planet Killer in this episode are referenced in The Next Generation novel "Vendetta." It was in the records Data was examining for a report for Picard. The first one was called a prototype, and the one Picard and crew face is the finished model. Larger, more powerful, and warp capable, this machine was driven by the vendetta of a person that wants revenge on the Borg.
Answer: Kirk was getting his physical and Dr. McCoy probably turned off communications, because if he hadn't, Kirk would have left and headed straight for the bridge, leaving McCoy irritated.