Many years ago Alfred Hitchcock introduced a generic name, MacGuffin, to cover all the missing, concealed or stolen objects which the characters in melodramas conspire to possess. The Maltese Falcon remains the most satisfying MacGuffin in the genre, closely rivaled by "George Kaplan," the nonexistent Movies spy in Hitchcock's "North By Northwest." The pirated tape recording in "Diva" is a cleverly updated example.

The only intriguing aspect of the strenuously trivial "Hanky Panky," a wheezing attempt at a romantic comedy-thriller now at area theaters, is the classified information supposedly encoded on its MacGuffin, a spool of computerized tape. For a few moments the display of computer graphics suggests a potentially sophisticated improvement on the tradition of cryptic messages or crumbling fragments of treasure maps.

Unfortunately, it turns out to be a graphically interesting clue to something amorphous. Richard Widmark, a free-lancing renegade within the national security apparatus, will stop at nothing to purloin this Top Secret Loop. He's responsible for a bizarre, murky suicide that begins the story and for chasing architect Gene Wilder and reporter Gilda Radner, the romantic innocent bystanders, from Manhattan to Boston to Maine to Arizona in pursuit of the mystery tape, which has fallen accidentally into Wilder's hands.

However, it's impossible to guess what this object might mean to enemy agents, apart from prompt interception while flying over a military reservation somewhere near the Grand Canyon, the reception that awaits the hero and heroine when they decide to nose around.

"Hanky Panky" probably typifies the miscalculation that can be expected when filmmakers persuade themselves that they're operating in the Hitchcock tradition but lack the skill to invent either an acceptable plot or irresistibly amusing byplay. You keep registering the echoes from "North By Northwest," but they merely remind you that the model was more proficient and satisfying.

The success of "Stir Crazy" may have made director Sidney Poitier reluctant to put restraints on Wilder's characteristic anxiety attacks, but they seem to cry out for restraints as "Hanky Panky" lurches along. The lack of competing, contrasting funny performers probably exaggerates Wilder's irritating tendencies. Where "Stir Crazy" had Richard Pryor, a gallery of amusing supporting players and a script that at least originated with Bruce Jay Friedman, "Hanky Panky" has only Radner as an additional comic resource; but her material is so feeble--and her rapport with Wilder so tenuous, for reasons that are no doubt beyond her control--that she emerges from this would-be humorous costarring vehicle looking prematurely haggard.

Far from proving a mischievous little diversion, "Hanky Panky" is the sort of runaround that ultimately wears down the patience of even undemanding audiences and does mischief--minor, one hopes--to the reputations of the performers and filmmakers involved.