I agree with you on Flash Gordon. The ending certainly left it open ended.
They PROMISED they'd be back. Never happened.
The teaser: Making the Grade, with Judd Nelson.
I really hated that movie, but the credits told us there would be a sequel.
Yes, agree with Flash Gordon.
Another tease. The end....?
Who picked up Ming's ring? And why do we hear his laughter?
To be serious for a second, a movie that cried out for a sequel was Starman.
I'd love to find out what happened when Jeff Bridges' son was born and became a "teacher".
But the movie really stands alone as a masterpiece.