Dwayne Johnson as Krypto and Kevin Hart as Ace in 'DC League of Super-Pets.'
CNN  — 

Who’s a good movie? Not “DC League of Super-Pets,” a big colorful idea that proves promising in theory – tailor-made for a two-minute trailer – but a rather tedious slog as a full-length animated film. Dwayne Johnson and Kevin Hart’s “Jumanji” reunion as the central voices and an intriguing start to serve up a few bones fun-wise, but not nearly as much as there should be.

Director/co-writer Jared Stern and script partner John Whittington have both worked on the Lego movies, and that history shows in the rat-a-rat barrage of gags that fly by, some clearly aimed at adults steeped in comic-book lore and others simply loud, goofy and designed for kids.

Yet after a visually impressive introduction that playfully rewrites the 1978 movie “Superman” – having a puppy-sized Krypto (Johnson) stow away on baby Kal-El’s ship to Earth – the movie yields diminishing returns, with the cleverest gags too heavily outnumbered by those that fall flat.

Poor Krypto has grown up with an enviable canine existence, enjoying regular walks (OK, dazzling flights over Metropolis) with his master and even helping him fight crime. He’s thus stricken and jealous when he realizes that Superman (John Krasinski) is spending way more time with Lois Lane (Olivia Wilde), feeling like the odd mutt out.

The pity party can’t last too long, because a guinea pig who once belonged to Lex Luthor, Lulu (Kate McKinnon, completely unleashed), acquires orange kryptonite, giving her extraordinary powers. That event also bestows lesser skills upon the ignored shelter pets with her, including Ace (Hart), a dog with a “Toy Story 2”-worthy back story; PB (Vanessa Bayer, adding to the “SNL” connection), an emotionally needy pot-bellied pig; a daffy squirrel named Chip (Diego Luna); and Merton (Natasha Lyonne), a near-sighted turtle suddenly imbued with – what else? – super speed.

At first blush, Krypto’s exposure to a more grounded pet’s-eye-view of the world seems filled with possibilities, and there’s a long track record of major franchises built around anthropomorphic animals. In addition, the producers pepper the movie with knowing references and nifty little flourishes, such as having Keanu Reeves provide the voice of an especially tortured Batman, who stresses that his only experience with pets is being swarmed by feral bats.

Despite the brawny action sequences, the movie suffers from an arid stretch in the middle when many of the jokes fall flat, and the common miscue of a climactic sequence that drags on. The main problem, though, might be the way the movie oscillates between insider-ish humor and the broadest kind of dog-related gags, until you begin to wonder precisely for whom it’s intended.

Obviously, silliness has found a receptive animated home with the latest iteration of the “Minions” franchise, but combining that sensibility with the DC brand – which regularly churns out more adult-oriented animated movies straight to Blu-ray – requires a balance that “League of Super-Pets” doesn’t consistently achieve.

Then again, the main “super-pets” here were introduced in the mid-1950s, generally considered a sort-of low point for this quadrant of the comics industry, so expectations should have perhaps been tempered accordingly.

Whatever the cause, “DC League of Super-Pets” plays like a super-team underachiever, if one where there won’t be many howls to release the director’s cut.

“DC League of Super-Pets” premieres July 29 in US theaters and is rated PG. It’s being released by Warner Bros., like CNN, a unit of Warner Bros. Discovery.