copyright 2009, The Washington Post 'Planet 51' is cute. Cute, however, is a double-edged sword. The animated movie succeeds as a gently wry twist on 'E.T.: The Extra-Terrestrial,' in which the 'alien' is a human astronaut (Dwayne Johnson) who gets stuck on a planet of little green men and has to enlist the help of a plucky youngster, Lem (Justin Long), to get home. But it's no great beauty. That's not just because of some unnecessarily coarse humor. Johnson's character, Capt. Charles Baker, uses the euphemism 'fricking,' and there's a sight gag about his, er, 'antenna' when he jumps naked off an examination table. And Lem's friend Skiff (Seann William Scott) proposes an unorthodox use for a champagne cork as a means of protection from the dreaded anal probe that he supposes Baker is going to use on him. Yeah. Like most little kids have even (ital) heard (end ital) of that form of cultural outreach. Of course, the aliens -- who, like Donald Duck, wear shirts but no pants -- are as squeaky clean as a Ken doll from the waist down. So the joke doesn't even make sense. That's the thing. 'Planet 51' wants to be a kids' cartoon, but it's written as if it's for grown-ups. One of the film's recurring gags is that the residents of this planet are still stuck in their version of the 1950s, while Baker is from today. (The film's title can be read as both a play on Area 51 and a reference to the decade in which it seems to be set.) The standard attire for Lem -- Get it? Lunar excursion module? -- is a bowling shirt. 'Cars' are wood-paneled hovercraft. And telephones are still rotary-dial. Cute. But over the heads of most young audience members, who won't know the 1950s from the 1940s. Or the 1960s, for that matter. Neither, apparently, do the filmmakers (writer Joe Stillman and directors Jorge Blanco, Javier Abad and Marcos Martinez). One of the movie's characters is a long-haired hippie alien named Glar (Alan Marriott) who's protesting the military's bellicose response to Baker's arrival. Glar, a rival for the affections of Lem's love interest, Neera (Jessica Biel), drives around the town of Glipforg in a psychedelic-painted UFO that looks suspiciously like a VW van on the way to Woodstock. Again, this makes no sense in a movie whose soundtrack features '50s hits 'Lollipop' and 'Mr. Sandman.' But does any of this really matter? The 'E.T.' template is a safe one. At this point, who hasn't seen the movie, either on cable, DVD or when it first came out? So 'Planet 51's' table-turning premise -- and recycled warm fuzzies about embracing the Other -- is guaranteed to get at least a few laughs. In the end, though, 'Planet 51' may bear less similarity to that 1982 movie than to a much more recent film, not coincidentally also starring a funny-looking guy with green skin and antennae. Writing in the New York Times magazine about the influence of 'Shrek' on subsequent kids' movies, A.O. Scott notes how that animated 2001 feature 'set the template for 21st-century family entertainment.' 'License a lot of pop songs,' he writes of the now-sure-fire formula, 'lock in merchandising opportunities, recruit A-list celebrities to read a script full of winking allusions and semi-rude jokes for the grown-ups and hokey morals for the kids, and watch the money pour in.' 'Planet 51' is cute, but it's no 'Shrek.' -- 'Planet 51' (PG, 90 minutes) contains sci-fi action and suggestive humor. 