As a nostalgic evocation of Hollywood in its heyday, "Under the Rainbow" is a facetious abomination. Opening today at area theaters, it ranks right down there with "Nickelodeon," "W. C. Fields and Me" and "Gable and Lombard." As an example of aggressively mirthless movie farce, it invites humble comparison with Otto Preminger's "Skidoo."

A regrettable misstep taken by the same group that made an auspicious feature debut on "The Buddy Holly Story" -- director Steve Rash and producers Fred Bauer and Edward H. Cohen -- "Under the Rainbow" derives from a sidelight to the production of "The Wizard of Oz." Most of the midgets recruited to play Munchkins were lodged at the Culver City Hotel near the MGM studio.A few hard-core drunks and libertines created a legend of rampant hedonism around the little people in general. It's the sort of Hollywood scandal that probably tempted scores of comedy writers, until they did enough research to discover that the rumors of gross misbehavior were exaggerated.

Nevertheless, Rash and his associates walked right into this vintage boobytrap, equipped with a desperately gaggy script and exposing a brutal lack of comedy style or judgment. The results couldn't be less appealing or more disreputable. Adam Arkin, Alan's son, who plays the harried young assistant manager of the hotel, gets a line that sums up the general disgrace: "Is my future going down the drain?"

Predictably, the writers fail to sustain a farcical plot on the pretext of midgets running wild at the Culver City Hotel. They cook up a farfetched case of international intrigue to justify the oafish procession of sight gags, chases and lewd one-liners. Billy Barty, a diminutive Nazi spy, arrives at the hotel seeking a Japanese agent, played by Mako. By the time they check in, the joint is already jumping with midget and Japanese guests. The midgets, of course are working for MGM. The Japanese belong to a tour group of shutterbugs called the Japanese Amateur Photographic Society (heh-heh). The tourists dress in identical white suits and hats, and so does Mako. This profusion of midgets and Orientals makes it difficult for the two spies to identify each other promptly, provoking inane complications.

The unlucky leading man, Chevy Chase, checks in with a supplementary intrigue: He's supposed to protect a jittery nobleman, the duke of Luchow, from being assassinated by a shadowy, fanatic Italian. The unlucky leading lady, Carrie Fisher, is supposed to be the MGM talent coordinator charged with looking after the Munchkins. She becomes entangled with the gummy frenzy after loaning a copy of the "Wizard" script to a friendly Japanese tourist in the hotel dining room, a truly incredible act for a studio employe of that or any other period. It's deemed necessary in these circumstances to enable Barty, mistaking this Japanese gentlemen for his contact, to slip the secret info (a kind of treasure map reputed to be our "mainland military defenses") inside the manuscript.

The level of wit is accurately reflected in jokes like the Japanese Amateur Photographic Society or the name of the studio boss, Louis Zeemeyer, or the name of the house detective, Tiny, played by Pat McCormick (who also contributed to the wretched script).

Towering over a crowd of little folk, McCormick observes, "This looks like an aerial view of an unemployment line."

The only effective gag is a running sick joke -- the pet dogs of the duke and duchess of Luchow keep getting bumped off. Chase and Fisher look as if they shared a certain apprehension about this project, but it's obviously too late to squirm out gracefully. Joe Renzetti's score is relentlessly jaunty, but Rash's ineptitude probably obliges a composer to attempt some form of busy-busy cover-up. There'd be too much dead air on too much dead space if he didn't try to slap on a few musical coats.

Eve Arden, affecting a Viennese accent as the duchess, slips in a deft stroke or two, including a funny exchange of slaps with Barty. Arkin, who looks like the young Richard Nixon from certain angles, shows a little style, and there's a robust performance from Cork Hubbert as Rollo, the most valorous of the midgets. The hint of romantic interest between Hubbert and Pam Vance as a miniature cutie lodging at the hotel might have given the movie an ingratiating subplot if smartly developed. The Chase-Fisher romance is a hostage to dumb characterizations and dumber innuendo from the outset.

That's about the size of it.