`MST 3000' PLAYS SOPHOMORIC HUMOR TO THE HILT.

Byline: Bob Strauss Daily News Film Critic

This week's television program with a glandular condition is ``Mystery Science Theater 3000: The Movie.'' It's a big-screen version of the Comedy Central cable series, in which astronaut Mike Nelson (played by actor Michael J. Nelson) is trapped on a space station, where he's forced to watch bad '50s sci-fi movies with a couple of wisecracking robots.

So what we have here is a movie based on a cable show about watching bad movies. This would be as rock bottom as pop culture gets if the film weren't such a side-splitter.

Admittedly, despite the fact that the show won a Peabody Award, ``MST 3000: The Movie,'' like the series, is no masterpiece of sophisticated wit. Its humor, though well-informed, is primarily sophomoric, heavy on sexual snickering and ``you're-so-stupid'' putdowns. But it's also intermittently hilarious, and when the target, as here, is something as stiff and dopey as ``This Island Earth,'' the snot-boy attitude could not be more appropriate.

The cheesy 1954 production comes ripe for ridicule. It has supposedly brilliant scientists with all the observational powers of grapes. It has aliens with big foreheads who everyone relates to like they were only from France. It has rubber-suited space monsters, silly-looking UFOs and a ridiculous plot that, although obviously truncated (the original film was 86 minutes long; ``MST 3000: The Movie'' runs 74 minutes - intros, breaks and all), probably didn't make much sense to begin with.

All the fun in ``MST'' is concentrated in the movie-watching portion. Wraparound and intermission sequences explain a mad scientist's (Trace Beaulieu) plan for world conquest through torturous entertainment and showcase the eccentricities of Nelson and his mechanical companions. These segments are uniformly mirthless.

And while the sarcasm that accompanies the ``Island Earth'' screening is by nature hit-or-miss, there are so many zingers - and so many that are subversively hilarious - that you'd have to be an android not to laugh long and often at ``Mystery Science Theater.''

For a movie that cost about three cents to make, that's really snatching entertainment out of the trash compactor.

The facts The film: ``Mystery Science Theater 3000: The Movie'' (PG-13; language, violence).

The stars: Michael J. Nelson, Trace Beaulieu, Jim Mallon, Kevin Murphy.

Behind the scenes: Directed and produced by Jim Mallon. Written by Mallon, Michael J. Nelson, Trace Beaulieu, Kevin Murphy, Mary Jo Pehl, Paul Chaplin and Bridget Jones. Released by Gramercy Pictures.

Running time: One hour, 14 minutes.

Playing: AMC, Santa Monica; Sunset 5, West Hollywood; Goldwyn Pavilion, West Los Angeles.

Our rating: Three stars