The E! entertainment channel's new documentary about the classically ridiculous sitcom "Gilligan's Island" may be more entertaining than the show itself ever was. Not that "Gilligan's Island" doesn't deserve respect. Any series that has been thriving in reruns for three decades merits admiration and maybe even awe.

"Gilligan's Island" has unquestionably become part of the culture--a masterpiece of kitsch--as succeeding generations of kids discovered it on local stations and memorized its universally recognizable expositional theme song. No matter how much you think you don't care about the show, you may still find "Gilligan's Island: The E! True Hollywood Story" airing on the cable network tomorrow at 9 p.m., to be two hours of fascinating fun.

Actually--something less than two hours. E! has gaping and frequent commercial breaks. In addition, each break is preceded and followed by a "coming up" teaser designed to keep you watching. There's probably 85 minutes of actual show there at best, but it's still an oddball treat, perhaps the best of all bets for tomorrow night's viewing.

Not only have TV critics--most of 'em--always hated and derided "Gilligan's Island," the slapstick comedy about seven castaways stranded somewhere in the Pacific, even the network executives who put it on the air detested it. "Couldn't stand it," says Mike Dann, a top CBS programmer when the show aired from 1964 through 1967. "I didn't like it at all. . . . I never knew anybody in programming who liked it."

Adds Perry Lafferty, another former CBS executive, "The network knew the show was terrible. . . . Network brass were . . . embarrassed by the show." Russell Johnson, who played the Professor, says that after reading the first script, "I had no faith in it whatsoever."

CBS executives, however, were not embarrassed by the ratings. The show roared into the Top 20 soon after it premiered, and even moving it twice to different nights couldn't hurt it much. It would certainly have stayed on for a fourth season if not for a fluke of fate. Then-CBS czar William S. Paley returned from vacation to find that his favorite series, "Gunsmoke," had been canceled by his own programmers. He ordered it restored to the schedule. To make room, "Gilligan's Island" had to be canceled, even though cast and crew had already been told they'd been signed for another year.

The E! documentary is stuffed with this kind of irony, trivial or not. Comic Jerry Van Dyke was originally offered the part of Gilligan, the innocent doofus who is first mate on the stranded ship, and turned it down because he thought the script was "just awful . . . just terrible." Instead he signed on to star in NBC's "My Mother the Car," an infamous flop that was quickly canceled and that, in the history of crummy pop culture, ranks far, far lower than "Gilligan" does.

Of course Bob Denver was the actor who eventually played the role, with Alan Hale Jr. as the Skipper. They were an engaging Laurel-and-Hardy combination, the portly Hale doing sterling slow burns at hapless Gilligan's hopeless bumbles. This inspired teaming was key to the show's success, and it helped the public ignore the preposterousness of the premise.

In an interview taped for some previous documentary, Denver says in the show's defense that "silly" comedies are important components of TV's palette of escapism: "There should be one or two on television all the time."

Repeatedly, the story of how producer Sherwood Schwartz battled with the networks, first to get his show on the air and then, later, to revive it as a two-hour movie, reveals how shortsighted and out-of-touch network executives can be--and arguably always will be. They may have hated "Gilligan," but the public loved it.

The CBS brass who were so embarrassed by "Gilligan's" cheerful nuttiness were at that time ruling the Nielsen Top 10 with such contrastingly sophisticated fare as "The Beverly Hillbillies" and "Gomer Pyle, U.S.M.C." The Tiffany network has always been home to some of the most fatuously hypocritical executives in all of television, and this tradition will apparently continue right on into the next millennium.

Although it's hardly a classic in the "I Love Lucy" league, "Gilligan's Island" still has found a spot as one of the most enduring situation comedies of all time.

Three key cast members are gone now: Jim Backus and Natalie Schafer, who played the dizzy millionaires Thurston and Lovey Howell, have died. Hale has also passed away. But they are all pretty much guaranteed immortality.

Another cast member, Tina Louise, is alive but won't speak of the series, and reportedly blamed it for ruining her serious acting career. Other cast members say she was difficult to get along with and, apparently, the only real grouch in the group. She did not appear in the 1978 reunion movie, "Rescue From Gilligan's Island," because she demanded twice the $50,000 fee that all the other cast members were getting. Schwartz refused to ante up.

By that time, history had repeated itself. Schwartz first started peddling a "Gilligan" reunion in 1974 and was again met with snobbish rejection by executives from all three networks. Finally in 1978, Fred Silverman, a fairly recent arrival at NBC, gave Schwartz the green light. Result: a 52 share, absolutely enormous even by the pre-cable standards of the time.

Much of the "Gilligan" lore in the documentary has already appeared in books by, among others, Denver, Schwartz and Backus, but the two-hour show makes for convenient packaging--or repackaging--and includes home movies taken on the set by members of the cast.

Certainly the little band of castaways is now officially a pop icon. Dawn Wells, who played Mary Ann, is currently appearing in a Western Union commercial (included in the documentary) that lovingly spoofs the show, and when a show is this dumb yet innocent, lovingly seems the only way to spoof it.

It seems that no matter what--Hell, high water or something in between--"Gilligan's Island" will be with us forever. This charming look backstage is enough to make you glad it will be.

'Witness Protection'

"Witness Protection" doesn't make a very tempting recruitment film for the witness protection program. But it is quite a showcase for actors. Just about every major player in the movie gets a chance to go bonkers, stage tantrums, have crying fits or scream bloody murders.

The HBO film, premiering tonight at 8, is certainly well made, but it's very depressing and wildly melodramatic. It's the story of a family forced virtually to shed its skin and become different people so that federal authorities can ship them off to a new location where the mob, it is hoped, won't find them and kill them.

Bobby Batton, played by Tom Sizemore, is a middle management mobster who goes to the FBI when he finds out that someone else in the organization has jeopardized his future there. He has few choices that will keep his wife, son and daughter--and himself--alive, and one of them is entering the witness protection program operated by the bureau and the U.S. attorney's office.

In return for testifying against the Mr. Big of the Mob--a man named Theo, whom we don't meet--Bobby and his family will be given new names and new identities and shipped in secrecy from Boston to their new home in Seattle.

The film was clearly made to capitalize on HBO's success with its brilliant mob drama "The Sopranos," which returns next month, eagerly awaited. Although the two shows are completely different in tone, Sizemore, probably not by coincidence, bears a certain physical resemblance to James Gandolfini, star of the series. He's not nearly as good, however.

The movie, written by Daniel Therriault and directed by Richard Pearce, tries to show the practical problems and hardships that relocated informant families undergo. There are dozens and dozens of adjustments to be made. The Battons are sent to a fortresslike federal facility to learn their new ways of life, new names, even new habits. Wife Cindy Batton, played by Mary Elizabeth Mastrantonio, becomes wife Joan Cooper and is told to stop fiddling with her collar, as she's been doing subconsciously for years, lest she give away her true identity.

Forest Whitaker, who plays the gentle and extremely patient federal agent who guides them through the program, has to deliver lots of very bad news with as much delicacy as possible, including the fact that the Battons may have been affluent but the Coopers ain't got a nickel. Contrary to what some of us may think about the program, the government apparently doesn't provide for the families' financial futures.

The fact that every member of the family has a grievance about the changeover, and either whines about it or pitches a fit, makes the film monotonous after a while, and not a very long while either. Mom cries copiously, little Suzie (played by Skye McCole Bartusiak, whose name is bigger than she is) cries hysterically, and near the end of the film, even surly and pouty teenage son Sean (Shawn Hatosy) gets tearful. In fact, he freaks as soon as they move into the federal facility and he realizes that "I'm missing my skateboard magazines." The horror, the horror!

"Why is Sean crying?" little Suzie asks later in the film, when he has another breakdown. Because, honey, in this movie, everybody cries. That is, they cry when they aren't shrieking at one another. Papa Bob begins to suspect even members of his own family of possibly having leaked information to mobsters, which has forced him into this predicament.

Viewers should be warned that "Witness Protection" would be rated R if shown in movie theaters because of strong language and violence. To scare the Battons into remaining in the program, the feds show them gory photos of mob victims, including pictures of slaughtered children; this hideous detail could very well have been omitted.

The classiest thing about "Witness Protection," really, is the opening credit sequence, brilliantly devised by Pablo Ferro. As for the rest of the film--it's an ordeal only for the stout of heart and strong of stomach.