So Jimmy Fallon leaves “Saturday Night Live” and immediately starts making bad movies. And the circle of life continues.

“Taxi” is the sort of bad movie that any hack director with a big budget, willing actors, and a shortage of good ideas can make. Like most action-comedies of recent years, it believes “loud and fast” are the same thing as “funny,” and also that African-Americans being loose and sassy while their white counterparts are bumbling and squeamish is sure-fire comedy.

On that skeleton of a concept the film hangs its flimsy plot. A New York City bike messenger named Belle (Queen Latifah) has just achieved her goal of becoming a cab driver, and she comes to the job prepared: She has spent the last five years pimping out her vehicle with various turbo boosters and other “Fast and the Furious”-style paraphernalia. How she obtained a New York City yellow cab to work on in her garage all that time is anybody’s guess, as is the question of how she convinced her new cabbie bosses to let her drive it, especially with all its illegal alterations, rather than a company-issued vehicle.

At any rate, thanks to her hair-raising driving and maneuvering skills, she can now make it from midtown to JFK in less than 15 minutes. This makes her the perfect accomplice when an on-foot police officer named Washburn (Jimmy Fallon) hops into her cab one day and orders her to proceed to a nearby bank where there is a robbery in progress. Washburn is a terrible driver and previously was relieved of his license by his impossibly hot lieutenant (Jennifer Esposito).

The robbers barely escape after a chase through Manhattan, but the cops figure out it’s part of a string of robberies, which means Washburn and his new buddy Belle will get to pursue them some more.

The movie, based loosely on a French film, was written by Ben Garant (of TV’s heavily improvised “Reno 911,” suggesting his skills are in improv, not writing) and directed by Tim Story (“Barbershop”). Its action sequences are competently shot and edited, but its comedy is a lame assemblage of old jokes and awkward punchlines, a typical cop comedy where the police never call for backup and are always shooting things. I give it credit for this, though: At least the “odd couple” angle between Belle and Washburn isn’t overplayed. They work more as partners than as adversaries, which is a welcome relief.

Latifah and Fallon are both funny people, and you can see them occasionally straining to break free of the mediocre script’s confines. Spiced up a bit more, this would be a fine role for Latifah’s sensibilities. I wish I could say the same for Fallon, but the baby-faced man with the dorm-slacker demeanor looks like anything BUT a police officer, and he makes no attempts to, you know, maybe ACT like one. He acts like himself, a move that might work in some circumstances but that absolutely fails when he’s playing as specific a character as a New York City police officer. Maybe Fallon is a good actor, but we’ll have to wait for another movie to find out.

D (1 hr., 37 min.; PG-13, lots of profanity, one F-word, a little sexual innuendo.)