Balance of Terror: Opening planet
Geologic features are visible on a new computer-generated planet as the Enterprise flies by during the opening credits
Balance of Terror: Romii or Remus?
Surprisingly, no changes to the viewscreen display. At the very least, I would have expected Romii (Rom II?) to be changed to Remus.
Captain Kirk even mentions Remus by name in his log entry at the beginning of the episode.