With “Underdog,” Hollywood once again demonstrates its ability to take a mediocre idea and destroy what little potential it had. They offer a graduate-level course in this skill at Disney University.

The “Underdog” cartoon series of the 1960s and ’70s was a spoof of “Superman” in which a mild-mannered canine could trot into a phone booth, change into a costume, and fly off to save damsels in distress. Underdog often spoke in rhyme, which was probably amusing, or at least cute, coming from a cartoon dog.

The new “Underdog” film is live-action, with the talking animals’ mouths moved via computer wizardry. Switching from the cartoon realm to real life immediately saps a lot of the whimsy out of a project. Things that made sense in a cartoon — or that you had no problem overlooking because it was a cartoon — start to stick out when they’re transferred to the real world.

Personally, I kept getting hung up on Underdog’s paws. How does he put on his costume, or pick things up? You need thumbs for that. Or at least fingers. A cartoon dog’s paw can sort of anthropomorphize into a hand when some kind of gripping action is necessary, and you buy it. But a real dog’s paw can’t do that. So in the scene where Underdog takes Polly (his Lois Lane) flying over the city, he tells her not to worry, he won’t let go of her — but I just kept thinking, “How are you even holding onto her?!” She just had her paw sort of draped over his. HOLY CRAP, SHE’S GONNA FALL!!

But anyway. Nearly every element of spoof or satire is gone in the live-action version. Some details parallel the Superman model, but they come off as dumb, not clever. And all that rhyming he does? ANNOYING. Why does he do that? Just because that cartoon did? Sorry, but that’s not a good enough reason.

Jason Lee is the voice of Underdog, a washed-out police beagle who gets kidnaped by a mad scientist (Peter Dinklage) and given superpowers in a lab accident. He escapes and finds a home with Dan Unger (James Belushi), a cop-turned-security-guard who gives the dog to his teenage son, Jack (Alex Neuberger), as a pet. They name him Shoeshine. Jack soon learns of Shoeshine’s abilities — including being able to speak English — yet hides them from his dad. No explanation is given for this secrecy.

Jack likes a girl named Molly (Taylor Momsen), who has a dog named Polly (voice of Amy Adams), whom Shoeshine has a thing for. As Underdog, he fights crime and saves humans from peril. As Shoeshine, he’s ordinary and unremarkable. The mad scientist threatens the city, claiming he’ll make them pay for what they did to him, although it’s never indicated what, exactly, he thinks the city did to him. (He was injured in a fire, but that was his own damn fault.) People are in danger. Underdog saves the day. Et cetera.

The screenplay, credited to Adam Rifkin (the stupefying “Zoom”), Joe Piscatella, and Craig A. Williams, relies lazily on your basic dog jokes: pooping, dragging their butts across the floor, drinking out of the toilet; you know the routine. (I confess to chuckling at Shoeshine’s delight at discovering the sport of baseball: “Sticks, balls, and running, all in one game?!”) And I note that the director, Frederik Du Chau, also made “Racing Stripes,” which also had talking animals. So I guess he’s got that niche filled. You want a cheap, halfhearted comedy about talking animals and lots of poop jokes? Call Frederik Du Chau.

So here’s a live-action version of a cartoon that originally aired 40 years ago. The movie is meant for kids, but of course kids have no idea who Underdog is. (The film even starts with a clip from the cartoon, for no reason other than to let you know, “Oh, hey, this is based on a cartoon.”) And yet the film insists on including minor details from the cartoon, as if to appease the fans, and these details are awkwardly crammed into the movie in a way that renders it nearly nonsensical. You want to make a movie about a dog who’s a superhero, fine. But you should probably start from scratch, not try to adapt an old product from a completely different medium.

Oh, and a good script with some funny jokes and a story that makes sense wouldn’t hurt, either. Y’know, if you can manage it.

D+ (1 hr., 24 min.; PG, some crude humor, mild action violence.)