Greg Cox wrote:
It's probably worth noting that the first Christopher Reeve "Superman" movie, which came out around the same time, went the same route: Superman: The Motion Picture.
Almost -- it was Superman: The Movie
Yeah, but the title as presented in the film was just plain Superman,
with no subtitle.
I'd be curious to know why it was marketed as Superman: The Movie.
(Pending documented confirmation, the "event" idea certainly sounds right.)
On the other hand, in the case of Star Trek,
the subtitle was and is included, when presented in the film Star Trek: The Motion Picture.
(The colon was not typed, but the colon is common style for separating title and subtitle.)