Cast and crew err on the side of silly in “Journey 2: The Mysterious Island,” the amusingly childish sequel to that unlikely 2008 hit “Journey to the Center of the Earth.” They’ve rendered Jules Verne’s novel into a jokey lark, with broad, corny wisecracks, comic sidekicks and everybody riffing on the gi-normous lizards, humungous spiders and the like.

For those who have forgotten the conceit, the idea here is that while “most consider” the stories of 19th century novelist Jules Verne “works of science fiction, Vernians know otherwise.”

Sean Anderson (Josh Hutcherson) certainly does. He lost his dad on an epic “Journey to the Center of the Earth.” Now, years later, living with mom (Kristin Davis) and an over-compensating step dad, Hank (Dwayne Johnson), the re3bellious teen gets a coded radio message from grandpa. Since contractor-step dad used to be a Navy code breaker, they quickly realize the message is “The Island is real.” That would be Verne’s “Mysterious Island.”

And they know where it is. That sets the stage for a step-father/son bonding trip to the South Pacific, where they hire a low-rent chopper pilot (Luis Guzman, funny) and his daughter, given a teen va-va-voom turn by Vanessa Hudgens.

They find the place all right. And grandpa, played by Michael Caine in Indiana Caine mode — an aged joker stranded in the jungle.

“Don’t just stand there — APPLAUD!”

The script makes gramps and Hank comic foils, with lots of “my large friend” vs. “old man/old ladies” cracks. As in, “Bef careful. Medicare doesn’t cover old ladies falling off gigantic bees.” Because yes, there are gigantic bees, and poodle-sized elephants, a boiling volcano, but not — one must say — much menace. We never fear for anybody, and the action scenes are little more than 3D showcases ripped off from the “Star Wars” movies.  Director Brad Peyton plays around with slo-motion 3D, just for fun.

Which is the way to treat the whole enterprise. It’s not Vernian or groundbreaking or smart or even that clever. This “Journey” is an action film for pre-teens, squeaky clean and scare-free. There’s not much here for grownups, but then, the actor formerly known as “The Rock” makes a perfectly appropriate, perfectly adorable (He plays with his pecs, and even sings a ukelele ditty) babysitter.

The most brilliant thing you’ll see in “Journey 2” is the cartoon short attached to the front, a new computer-animated Looney Tunes romp that uses an old record the late Mel Blanc made as Daffy Duck duck back in the 1950s. “Daffy’s Rhapsody” animates that operatic riff — Daffy singing about why he’s so “gosh-darned riff-raffy” to the tune of Franz Liszt’s “Hungarian Rhapsody #2” on stage as Elmer Fudd blazes away at him. The little black duck was made for 3D.

MPAA Rating: PG for some adventure action, and brief mild language

Cast: Josh Hutcherson, Dwayne Johnson, Vanessa Hudgens, Michael Caine, Luis Guzman

Credits: Directed by Brad Peyton, scripted by Brian and Mark Gunn, based on the Jules Verne novel. A Warner Brothers/New Line/Walden Media release. Running time: 1:30