Interesting parallel to Mork & Mindy. As I recall, part 1 of the two-part second-season premiere was filmed before Robin Williams left to film "Popeye." When he was available to film part 2, the hairstyling department could not match the way his hair looked like in part 1. They did their best and filmed part 2. To make matters worse, ABC showed both parts in an hour broadcast. Supposedly, when the show returned after the mid-episode break his hair looked different with no explanation.I saw it a few times when it came out. It's weird, and maybe even not so good, yet it has a strange fascination.
What bothered me about it is the pieces don't fit together; there are various shots culled from different takes with different lighting and timings patched together.
At a first viewing it seemed sloppy and somewhat incompetent, even to the point of having inserts of Williams and Duvall and Paul Dooley where they seem inelegant and going against the grain of the scene, as if Altman decided to place outtakes and bloopers into the main scenes.
Things don't match, either visually or continuity-wise. But on repeated viewings, you grow to accept this, though it's different from any other Altman film I've ever seen, even the really far out ones, like "Quintet".