For about 90 minutes of ``Explorers,'' director Joe Dante is on his best behavior. He builds the story, develops the characters, zaps us with computer graphics. It's science fiction by the numbers -- skilled, professional, and dull. Then, just when the plot seems headed for some bottomless black hole of the imagination, Dante cuts loose. For about 15 minutes the movie goes crazy -- jamming the screen with enough jokes, whimsies, and visual ideas to stock a dozen ordinary films.
This eruption of hilarity isn't enough to justify the whole picture, which unfortunately recovers its wits and steers to a crash landing. But it's exhilarating fun while it lasts.
``Explorers'' begins in a small town. It's respectable and boring, like most of the movie itself, offering no excitement for a teen-ager except dreams and fantasies.
For a bright schoolboy named Ben, the dreams have been unnaturally vivid lately. While his body sleeps, his mind flies through the innards of a giant computer, and he can sketch its construction after he wakes up.
Tantalized by these blueprints, his brainy friend, Wolfgang, feeds them into his own home computer and comes up with a mysterious object made of pure energy. Shaped like a sphere and hard to control, it's mischievous enough to scare the cat and knock dad's basement apart. But the boys, joined by their underprivileged pal, Darren, see its possibilities in a flash. Make it large enough, install a place to sit, and you'd have a backyard spaceship built for three.
Dante unfolds this part of the tale with plodding care, as if spacestruck kids and dreams-come-true were shiny new ideas, not gluts on the summer-movie market. Although the dream sequences are colorful, the human-interest scenes are trite, complete with schoolyard bullies and wistful gazes at the pretty girl in science class.
Even when he sets up a good situation, like the Spielbergian chaos of Wolfgang's nutty household, Dante lets it slip away after a few limp gags. The film loosens up a little when the boys build their spaceship from various oddments, yet the director still works by rote. He parodies low-budget movies, pokes fun at the cops, and smashes up a drive-in theater -- all ``correct'' moves for a picture like this, and all executed with a drab sense of directorial duty that leaves no room for enthusiasm or glee.
Things threaten to get even more pointless when the kids and their ship are whisked into outer space by an unseen force, but this gimmick leads to Dante's one burst of inspiration. Among the stars, the boys meet a family of aliens -- and they're hilarious.
Learning all they know of Earth from old TV shows beaming their way around the cosmos, these wacky space people woo our heroes with imitations of Monty Hall and rotten jokes from forgotten sitcoms. Their home is a seething mass of scrambled video images, their conversation a hopeless jumble of media stupidities. Dante has a ball with them, shaping their loony excesses into an explosive yet artfully structured sequence that bulges at the seams with verbal and visual invention.
Here at last is the irreverent Joe Dante who explored the underside of Spielberg's cuddly-creature syndrome in ``Gremlins'' and made the little-boy episode of ``Twilight Zone: The Movie'' into a true cinematic adventure. He takes a long time to conquer the cautious, conservative Dante who dominates most of ``Explorers,'' and his victory doesn't last long. But it's good to feel his energy, imagination, and sense of fun when they're allowed to surface for a few marvelous minutes.