It may look like heaven, but the spacious loft that houses Sunburst Communications — the new-age Ohio advertising agency where much of the comic mischief in “The Ex” is hatched — is a viper’s nest.

It’s the kind of place where the cheerless creative staff sits at a conference table each morning and tosses around an imaginary toy called the “yes ball” while juggling notions about how to sell “pickle whip.”

On his first day at work Tom Reilly (Zach Braff) tosses the invisible ball to his yuppie boss, Chip Sanders (Jason Bateman), unaware that Chip is a paraplegic and can’t stand up. After a collective gasp, Tom is told of Chip’s disability and grovels for forgiveness. It is the first of his many excruciating gaffes.

Tasteless jokes at the expense of the disabled roared back into style nine years ago with “There’s Something About Mary.” But “The Ex,” directed by Jesse Peretz from a screenplay by David Guion and Michael Handelman, feels less like a Farrelly brothers comedy than like David O. Russell’s “Flirting With Disaster.” The best jokes in this scattershot screwball satire of job insecurity, upward mobility, political correctness and yuppie marital tensions have claws that leave scratches.

Chip milks the role of macho victim for all it’s worth. He pressures a reluctant Tom into playing a vicious game of wheelchair basketball; the other paraplegics take offense when a battered Tom steps out of his chair at the end of the game. As the abuse accumulates, Chip, a master of dirty tricks, behaves so despicably that your impulse is to cheer when Tom finally pushes him down a flight of stairs.

Tom, a transplanted New Yorker and former cook, is already intimate with humiliation when he arrives at Sunburst. He and his wife, Sofia (Amanda Peet), have moved to Ohio with their newborn baby because Tom was sacked from his job at a restaurant after a fight with the sadistic head chef. He can run, but he can’t hide; apparently there are as many selfish, backstabbing sociopaths climbing the ladder in Ohio as in New York. That’s the way it is in these Darwinian times.

Adding to the pressure is Sofia’s decision to quit her job as a lawyer and be a full-time stay-at-home mom, forcing Tom to be the sole breadwinner — or else. It doesn’t help his self-esteem that his father-in-law, Bob Kowalski (Charles Grodin), who works at Sunburst and pulled strings to get him the job, enjoys reminding him of the risk he took.

Mr. Braff’s Tom is a softer variation on the intrepidly persevering schlemiel developed by Albert Brooks, Ben Stiller and Adam Sandler. High on Tom’s list of worries is the sense that he doesn’t deserve his beautiful wife, whom Chip, who dated her in high school, intends to steal. Tom may make Sofia laugh, but Chip is allegedly a dynamite lover despite his disability. In an outrageous throwaway moment, Chip woos Sofia by playing a video of the sex scene from “Coming Home.”

While Mr. Braff ambles agreeably through his turn as a crumpling cream puff, Mr. Bateman’s Chip hijacks the movie with his intimidating mixture of noble self-pity, bravado, cunning and cruelty. Mr. Grodin, making his first screen appearance in more than a decade, embodies the obsequious, glad-handing sycophant with a dark side. Mia Farrow, as his wife, is amusingly fluttery.

“The Ex” never quite delivers what it promises. As its pace quickens, it becomes increasingly sketchy and its parts begin to come unglued. You sense a lot of its subtleties have been dumped on the editing-room floor. The movie’s last-minute change of title from “Fast Track” to “The Ex” suggests how conceptually divided against itself the final product is. As it wavers between being a send-up of smiley-faced corporate duplicity and a sadistic comedy about a shark going after a goldfish, its identity becomes increasingly blurry.