There’s plenty of guilt to go around here—not, unfortunately, so much for the characters as for the filmmakers. The picture is a cross-country road movie in which the buddies are an overbearing mother and her browbeaten son. As written by Don Fogelman and directed by Anne Fletcher, “The Guilt Trip” has the look and feel of an extended sitcom, and a mediocre one at that. It’s barely an hour-and-a-half long, but seems to go on forever before reaching a destination that everyone in the audience will have seen coming from very far away.

The journey’s main distinction is the pairing of Barbra Streisand and Seth Rogen as Joyce and Andrew Brewster. He’s a nerdy, unmarried chemist who’s developed a wholly natural cleanser that he’s trying to sell to outlets across the country via one-on-one conferences. He flies to the East Coast for a visit with Joyce, his voluble, long-widowed mom, intending to leave by car (or more properly rented SUV) as soon as he can after being embarrassed in front of her friends. But when he discovers that she had a pre-marital fling with a man she still remembers fondly—and tracks the fellow down to San Francisco—he abruptly decides to invite her to tag along, intending to surprise her with a visit to the fellow as the final stop.

He soon regrets the decision, of course, as Joyce commandeers the trip in every conceivable way, from the choice of vehicle (she insists on a compact to save money) to their route (she’ll eventually arrange a stopover with Andrew’s old high school girlfriend and her husband, played by Yvonne Strahovski and Colin Hanks, along the way). She annoys him with her noisy snacks, her audio book and her accusatory prattle about how he decided to go to grad school as far away from her as he could get. And there are the detours (to the Grand Canyon that’s she’s always wanted to see) and stops where Joyce enthusiastically takes center stage (a Vegas casino where she gambles all night, a steakhouse where she takes on a challenge to eat a huge meal in an hour and get it free).

All this causes friction between the duo, of course. But in the end it’s all “Mother Knows Best,” since Andrew succeeds in his salesman role only after he gives up his ultra-scientific pitch in favor of something homier and more accessible, as she suggested. And what of that rendezvous in San Francisco? Well, it ends with a twist that will have been obvious to everyone but Andrew from the moment he planned it.

There’s nothing essentially wrong with a family reunion movie in which mother and son bicker but ultimately bond anew. But this one is as formulaic as Andrew’s miracle cleanser. It serves primarily as a vehicle for Streisand, who’s just her usual gregarious self as Joyce, blasting through Fogelman’s limp dialogue as though she were doing a self-impersonation on Saturday Night Live. She’s not a mother figure, of course; being who she is, she has to be Supermom, always proven right. She even gets the hint of future romance in a meeting with an admiring cowboy (Brett Cullen) at that steak joint.

As for Rogen, he defers to Streisand, muttering his responses almost sotto voce so as not to step on her laugh lines or interfere with her timing. It’s another instance in the recent string of pictures in which he’s damped down his brashness to some degree (“50/50” and especially “Take This Waltz”). But he’s serving a lesser cause in this instance.

Visually “The Guilt Trip” is indifferent, with a flat production design (Nelson Coates) and pro forma cinematography (Oliver Stapleton), and Christophe Beck’s score is, as usual, inconsequential. This is the sort of picture that simply doesn’t benefit from big-screen treatment; it will be perfectly suited to the tube.

Of course there will be those who will venture out just to see Streisand in a starring role again, and at least this picture avoids being coarse and offensive in the way the “Fockers” movies were. Others will be attracted by the presence of Rogen, a star of the new generation. But both mothers and sons should be advised that in spite of the temptation to go see it together, that wouldn’t be a particularly good idea. A later screening at home, when you can excuse yourself at will, would be a better choice.