Eddie Muller and I do have many areas of agreement, and one of them is a high regard for MOONRISE (which Eddie has in his Top 25 noirs, both as registered on his web site and in his votes in our old 2005 poll). Keep in mind that after WWII Republic (like Monogram) made a push for more lavish production budgets on certain "prestige" films; one of these was MOONRISE (the third of three Borzage films made for the studio).
While it's true that the film had limited production resources compared with a major studio, I'm not convinced that it would have really been better with more realistic backgrounds. I think Borzage, his DP John Russell, and art director Lionel Banks took great care in devising an overall production design that fit a conception of the film as a meditation on self-enclosure; so many of the scenes play off such a notion, and do so with an understated dynamism. Banks, a consummate pro (and with a number of big-name films in his resumé, certainly knew how to do more with less...
As for Clark and Russell, their more limited range seems to fit the roles they are playing--characters who initially talk past each other, but survive a protracted ordeal. I think Ida Lupino was just past the stage of playing a role like Gilly Johnson; whatever sweetness that had been part of her on-screen persona was pretty much MIA at this point in her career. Russell apparently had a difficult time on set, in part because there was some off-screen contretemps going on due to her friendship with John Wayne that had Wayne's wife in a lather, but she has some ver good scenes in the old abandoned mansion sequences.
And we'd be remiss if Harry Morgan wasn't singled out for his tremendous performance as the mute Billy, who has a pivotal role in the film vis-a-vis Dane Clark's character arc.
BLOOD ON THE MOON and MOONRISE, despite their "lunar connection," make for a strange juxtaposition. Did Alan do a book signing for his BFI-style book on BLOOD? That seems to be a primary reason why the film was added to several of the later FNF festivals.