BELA LUGOSI DIED MIDWAY through the shooting of his last film, but that didn't stop his directors from replacing him in the final scenes with an actor who looked nothing like him. The result was Plan Nine From Outer Space, among the most ludicrous and confusing cinematic concoctions ever. Rod Serling passed away suddenly, too, but that didn't stop a major New York bank from post-humously releasing a T.V. commercial starring him. To bemused viewers, Serling came off sounding farther into The Twilight Zone than he ever had as narrator of the show by the same name.

So when Peter Sellers succumbed in July 1980 to a massive heart attack, leaving his latest Pink Panther extravaganza only half-filmed, director Blake Edwards knew he'd be taking a big chance trying to salvage the movie. But Edwards went for it. He overhauled the second half of the original script, doing away with Sellers' Inspector Clouseau by having the bumbling detective's plane mysteriously vanish in mid-mission. He also brought in an inquisitive young French reporter; her search for the missing sleuth leads her to a host of Clouseau's friends, foes, colleagues and relatives. The resulting flashbacks--gleaned largely from unused sequences from the five previous Panther films--compose most of the second half.

And, all in all, The Trail of the Pink Panther works surprisingly well. The first half of the film--in which Clouseau jaunts around England and France, wreaking havoc on two countries that already have more problems than they know how to handle--proves once again that the versatile Sellers was the funniest comedian of our age.

Seeking a disguise, he ambles into a family costume shop. In just five minutes' time, he devastates the store and unwittingly compliments the wife on her tremendous, hairy fake proboscis--which turns out to be real. Back at the office, he accidentally sets his office on fire--and showers his irritated co-workers by triggering the sprinkler system.

On the way to England, disguised as a cripple, he somehow upends himself in a rest room--and nearly crushes a fellow passenger when he emerges. In a London hotel, he engages a clerk in a typically baffling conversation--and the misunderstandings caused by his mangled Franglais eventually lead to the partial collapse of the hotel. Sellers pulls off all this slapstick with the deftest of touches--his Clouseau never senses just how much damage he has left in his wake.

The detective is searching for the exquisite Pink Panther diamond, which has disappeared from the mythical Middle Eastern country of Lukash (as it did in Clouseau's 1962 debut film, The Pink Panther). His scourge and rival, Chief Inspector Dreyfus (Herbert Lom) is livid that the clumsy Clouseau has drawn another choice assignment. But the President of Lukash wants the renowned Clouseau--until, that is, he learns that he stands to make big bucks in insurance as long as the diamond remains missing. Shortly thereafter, Clouseau disappears.

The second half of the film is predictably somewhat less sharp. The numerous recollections of Clouseau are linked together by French television reporter Marie Jouvet (Joanna Lumley); her self-righteous journalistic fury at being "warned off" the Clouseau case by the detective's enemies was enough to make this reviewer reconsider his career goals. But the people Jouvet interviews en route to researching Clouseau's life generally hold their own, and Clouseau's doddering father (Richard Mulligan), a veteran wine grower who's sampled a little too much of his produce, is hysterical.

And there are, of course, the flashbacks: to Clouseau's domestic wars with his man-servant Cato, to his childhood and "accomplishments" sleuthing, and to his characteristic butchering of the English language. The second half of the film is, in a sense, the "Best of Clouseau"--and for Panther devotees, it is glorious.

BUT WAIT, YOU SAY, How come everybody's knocking this film? A legitimate question. There are three types of criticisms that have been leveled at The Trail of the Pink panther. They're all wrong. Here's why, in increasing order of frequency:

* Clouseau's disappearance is handled clumsily. Granted, director Edwards should have done something to avoid having to dub in Clouseau's voice, for the two times he does so are occasions for wincing. But in general, the disappearance is foreshadowed well by shots of Clouseau's enemies scheming, and followed up on briskly by the commencement of Jouvet's search for the missing detective. In spite of the inspector's absence, the action moves quickly, thanks to well-chosen flashbacks.

* The movie simply isn't funny. This is the same old pretentious, anti-anti-intellectual garbage that a small coterie of snooty brie-toting critics have been shovelling out ever since the initial Pink Panther, and it's as stupid now as it ever was. Just because a movie is all slapstick and zero social commentary doesn't mean it can't be uproariously funny. So you want relevance? Trail of the Pink Panther is actually a symbolic indictment of supply-side economics during a recession-plagued post-industrial era. Satisfied?

* The movie should never have been posthumously completed, out of respect for Peter Sellers. This is actually a surprisingly common criticism, and it's usually followed by: "He would've wanted it that way." But who knows what Peter Sellers would've wanted? The point is, the guy was a comic genius. It would have been a crying shame to waste the 45 minutes of hysterical new material that Sellers taped before his death--or, for that matter, the nuggets of previously unused sequences that compose the film's second half.

The acid test is really whether you laugh enough during the film to forget that you're actually watching a dead man. The first time I saw the movie, a large chunk of ceiling collapsed in the back of the theater just as the flashback sequence was coming to a close. Every head in the house swung around--not just out of ordinary curiosity, but almost as if, in some bizarre perversion of Sensurround. Sellers had survived and Inspector Clouseau had fallen through our ceiling after yet another battle with Cato. Soon. Blake Edwards is going to unveil a sixth sequel. Curse of the Pink Panther, and I, for one, am going to be watching the ceiling.