Donald Sutherland was doing a hippie “accent”, California surfer dude peacenik of the 1960’s. Totally anachronistic, but the movie wasn’t exactly a historical drama.
Mmm, no, I think it IS called Mid-Atlantic–at least that’s what it’s called these days. I’m not sure what the name is for that Thurston Howell III, “Connecticut Lockjaw” (although I like “Connecticut Lockjaw”!) but what’s commonly called “Mid-Atlantic” refers to vowel sounds in particular, and describes a style of speaking modelled on educated metropolitan easterners of the early-mid 20th century. When I was in acting school in the late 80s and early 90s, that’s how we referred to that 1930s style of speaking, though my favorite voice and speech teacher ridiculed the idea of some mythological “mid-Atlantic” region.
By the way, if we’re talking about Katharine Hepburn, then that’s a different story, but if we’re talking about Standard Hollywood English, then I would say “mid-Atlantic.” There are other exceptions: Jimmy Stewart (I don’t know where his accent comes from), or Cary Grant (who spoke in a version of what Americans call a Cockney accent).
Is what we’re talking about the weird sort of speech I call “Newsreel”, the best example of which would be the Carl Denham character in “King Kong”?