Rex Harrison famously endured getting urinated upon by real sheep during the filming of the 1967 musical “Doctor Dolittle,” while the 2020 version of “Dolittle” sees Robert Downey Jr. removing bagpipes from a CG dragon’s rectum before receiving a faceful of gastric wind as a reward.

Whichever actor had it worse, it’s the audience who loses. Downey’s revival of Hugh Lofting’s legendary loquacious veterinarian, one who can communicate with any member of any species, splats onto the screen like horse dung, with few laughs and no charm. Even the actor’s legendary charisma, which this project sorely needed, gets tamped down by making a depressed widower the hero of a kiddie movie and by having that widower mumble in an accent that’s possibly Welsh, perhaps Irish, maybe Scottish, but definitely the enemy of comedy.

“Dolittle” doesn’t have a fraction of the verve of the similarly misguided “Cats,” but it does share with that movie a staggering amount of “What were they thinking?” decisions, first and foremost is the idea of setting the film in the Victorian era but having the doctor’s chatty menagerie speak exclusively in 21st century online sass. (And it’s not just the animals; Michael Sheen’s villain at one point yells, “Read the room!” at an underling.)

It took four writers, including director Stephen Gaghan (“Syriana,” “Gold”), to cook up a tedious saga whereby Dr. John Dolittle (Downey) — shut off from the world since the death of his wife, an explorer — is coaxed back into it by the arrival of two kids: Stubbins (Harry Collett), an animal-lover who wants to become Dolittle’s apprentice, and Lady Rose (Carmel Laniado, FX’s “A Christmas Carol”), Queen Victoria’s lady-in-waiting, who hopes the physician can cure the severely ailing monarch.

Dolittle travels to Buckingham Palace, where he determines that the queen (Jessie Buckley, “Wild Rose”) has been poisoned by deadly nightshade, and the only cure is the fruit of the Eden Tree, the mythical plant that Dolittle’s wife died trying to find. With some coaxing from parrot Poly (voiced by Emma Thompson), Dolittle accepts Stubbins as a first mate, and they’re off on a sea adventure and grappling with the villainous plots of Blair Müdfly (Sheen) and Lord Thomas Badgley (Jim Broadbent) — the conspirators who poisoned Victoria in the first place — and pirate King Rassouli (Antonio Banderas, with heavily kohl-rimmed eyes), who has his own reasons for hating Dolittle.

There’s maybe one set piece (involving whale communication and assistance) that works, and one gag that pays off (involving “The Godfather,” so you know the kids will love it), but for the most part, “Dolittle” remains as semi-comatose as Queen Victoria. There’s a constant flurry of hubbub and incident, and the animals are voiced by an impressive array of slumming A-listers — including Octavia Spencer, Tom Holland, Marion Cotillard, Ralph Fiennes, Rami Malek, Selena Gomez, John Cena and Kumail Nanjiani — but none of them get anything particularly funny to say or do unless you think the idea of an ostrich with daddy issues or a tiger with a mommy complex are the height of comedy.

The film’s visual effects are seamless until they aren’t (Poly’s bright plumage against Dolittle’s gloomy, vine-covered home is a shock to the eyeballs), and editor Craig Alpert (“Deadpool 2”) tries but ultimately fails to cut through the sluggishness of the proceedings. The opening sequence involves 2-D animation with narration by Thompson; doing the entire movie that way would have been far more fun to watch.

While the voice actors sparkle to the best of their ability, what we’re left with on-screen are two young performers who have been directed to lean into kid-actor cuteness opposite Downey’s weird ravings, which seem to have come from another (also not very good) movie. Broadbent, at least, appears to be entertaining himself by going full Colonel Blimp; the less-fortunate Buckley picks up a paycheck for what amounts to a well-dressed nap.

By the time Dolittle enters the dragon, “Dolittle” has exhausted the goodwill of most viewers. Fans of Rex Harrison and Eddie Murphy don’t generally mention “Doctor Dolittle” as a career highlight for either actor, and Downey’s turn here will eventually generate similar silence. He can talk to the animals, but let’s not talk about it.

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