At least a couple of the summer's comedies have something besides low farce in mind. Between pratfalls, The Survivors and Trading Places take time to comment on fads and attitudes that deserve a bit of caustic observation - although they also trade in the rambunctious gags and hackneyed vulgarities that have become dubious fads themselves in recent years.
The serious undercurrents of ''The Survivors'' recall such earlier Michael Ritchie satires as ''The Bad News Bears'' and ''Smile.'' Again, the story is mostly an excuse for shooting well-sharpened barbs at a foible that irks the filmmaker. This time the plot centers on two likable losers being hunted by a killer after witnessing a crime. But the movie's main enthusiasm is for heaping scorn on the American weakness for weapons, macho posturing, and the cult of ''survival'' at any cost.
Ritchie approaches his target slyly. First he introduces his heroes (played by manic Robin Williams and shaggy Walter Matthau) and plunks them into a few rough situations, testing their personalities under fire. The real theme of the picture surfaces bit by bit, through absurd but unsettling details - beginning in the first scene, when Williams is fired from his job and a dignified secretary hauls out a pistol when he seems reluctant to leave the office.
The movie hits its stride when the men visit a gun shop - more like a supermarket, really - and Ritchie delares war on the fortress mentality behind such a place. It's a goofy scene, and more than a bit scary. It lets us know Ritchie means what he says, and prepares us for still more scathing attacks later, when the characters go to a ''survival camp'' whose graduates hope to outlive some ''disaster'' they think is lurking around the corner.