Revealing mistake: When McCoy is examining Charlie in sickbay, several shots of the diagnostic panel show a clear reflection of Charlie's upright profile. But Charlie isn't sitting up during the exam - he's lying flat on the table. The close-ups of the panel were shot while actor Robert Walker Jr. was either sitting or standing nearby. (00:04:10)
Revealing mistake: As Charlie watches the pole lowering into a square hole in the deck, the wood grain of the set piece is visible. The wood has been painted gray/silver to look like metal. (00:06:06)
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.