The Black Hole - Every time I watch this I'm convinced there's a good movie in there somewhere. There's a bunch of religious allusions in the earlier parts of the film that tie in to the ending that I'd never noticed. And the parallel between how Maximillian kills Anthony Perkins and how Vincent kills Maximillian.
The music is cool, but the tempo is all wrong for the action shoot-out scenes. The matte paintings are often really good too - until your eye is drawn to where the set stops and painting begins and it's... yikes. I wonder if they fixed this for Blu-ray. Might have a look on Disney+ and see what it looks like.
Someone needs to redo this and link madness to what we actually know about black holes - radiation, gravity distorting time etc.