I just came across this:
At one point, Data makes a reference to the Irish Reunification of 2024, and because of that, the BBC refused to air the episode. It didn’t air on the U.K. government’s station until 2007, though it did air on satellite and cable (sometimes with that reference cut), and was released unedited on DVD in the U.K.
The episode was Star Trek: The Next Generation, "The High Ground", the one where Dr Crusher is abducted by "terrorists".
Since Star Trek has always touched upon "touchy" subjects, I'm curious about any other examples of government censorship of Star Trek.