SKot said:

Westworld (1973)
Directed by Michael Crichton(!), the first film has only seen a bare-bones DVD release so far. However, there is an additional "Making of Westworld" DVD that was released separately.

That making of DVD is garbage. It's just a couple of very short fluff promotional pieces made back in the day, with very, very little interesting making-of content. What's worse, it's obviously gone through several video generations, and for some reason they have hosted introductions (circa 1980 by the looks of it), produced under the "it has to look like the Academy Awards" mindset, with a guy in a tux in front of lush crimson drapery. (Wow, it's a celebration! Break out the bubbly, we're in for quite a treat!) He actually says "so sit back, relax..." TWICE. I've never understood the need of some content producers to have someone tell us what we're about to see. Just show it already.

I guess it wouldn't hurt to include it in a preservation, though... if only ironically.

Netflix has it listed as a disc 2 for the film, but, as you say, it had to have been released separately. Looked like a different animal to me. Unique label, different distributor, etc.