There are loads of references to other sci-fi movies in Planet 51: E.T., The Day the Earth Stood Still, Star Wars, even to a cute little mutt with a head shaped like the monster from Alien that squirts acid urine. The movie, about a far-flung planet of green aliens whose civilization resembles 1950s malt-shop and doo-wop America, is also crammed with subtexts about the era's paranoias, from UFO invaders to McCarthyism.

What's missing is originality and story and inventiveness -- everything that would distinguish the movie from just another computer-animated 'toon to entertain the kids for 90 minutes. The premise of the film, directed by Jorge Blanco with lots of visual dazzle but little heart, follows the mayhem that occurs after an American astronaut (voiced by Dwayne Johnson) lands on the planet and befriends a planetarium worker (Justin Long) who tries to protect him from the military and scientists who assume the human has come to conquer them.

The fact that everyone speaks English is the film's first and more forgivable contrivance. Less easy to overlook are the characters' utter lack of curiosity toward each other (wouldn't an astronaut be at least a tiny bit intrigued by this civilization that exists in a supposedly barren planet?), or a robot probe that unfortunately recalls Wall*E at every turn or tasteless gags thrown in supposedly to tide over adult viewers (one of the aliens gives the astronauts a cork plug, in case the scientists decide to ``probe'' him) but instead come off as inappropriate.

The stakes of the computer-animation genre have risen so high that no matter how colorful and beautifully rendered a feature film may be, pretty pictures just aren't enough anymore. Cloudy With a Chance of Meatballs soared on a surreal, anything-goes energy that made you wonder if genius lunatics hadn't temporarily seized control of a studio. Pixar's films (with the exception of Cars) have repeatedly proven that when you build your movie around a reliable story, the outlandishness of your characters and situations don't matter.

Planet 51 proves that recreating the '50s with aliens is a cute idea, but cute doesn't sustain an entire motion picture. The idea barely holds for 10 minutes before you start feeling as stranded as the astronaut.

Voices: Dwayne Johnson, Justin Long, Jessica Biel, Gary Oldman, Seann William Scott, John Cleese.

Director: Jorge Blanco.

Co-directors: Javier Abad, Marcos Martinez.

Screenwriter: Joe Stillman.

Producers: Ignacio Perez Dolset, Guy Collins.

A Sony Pictures release. Running time: 91 minutes. Mild vulgar language. Playing at area theaters.