In the movies, the path to “slow” is a precarious one. Such roles can be awards bait, but in these more enlightened times, playing a character described as such is walking a minefield between cute and insensitive, patronizing and simply wrong-headed.

“Better Start Running” is a road picture romance about two slow folk who might just fall in love, if the FBI or the cops don’t shoot them first. It’s a comedy rich in characterizations, broad and mean and satiric around the edges, predictably warm and fuzzy in its leads. A couple of those supporting players make it watchable, all by themselves, and the leads are easy to spend time with.

We meet Harley (Alex Sharp of “How to Talk to Girls at Parties”) as he’s responsibly calling in an incident in which another fellow “got hurt real bad.” There was a girl there, too, he adds, “but she had nothing to do with it.”

The 911 operator would love details, but “I’m sorry. I have to go now. I’m going on the run.”

So these two high-functioning special needs colleagues from the big box department store All Shop jump into Harley’s ancient, piecemeal minivan and flee — hitting the roadside attractions stops listed on a kid’s restaurant placemat Harley kept from way back when.

The siren whose predicament inspires this escape is Stephanie (Analeigh Tipton of “Two Night Stand” and “Crazy Stupid Love”). She’s scatter-brained in the extreme, overly fond of a label maker she stole at work, clinging to customer’s babies entirely too tightly, struggling to fit in with her mean girl customers, sexually mature even as she’s dodging the advances of their creeper boss (Chad Faust).

Yeah, he’s the one Harley has to call the cops about after he somehow got “pushed out a window.”

Their quest? Getaway, grab grandpa and dash off to Montana, home of “The World’s Largest Gun” and Grandpa’s pre-Vietnam love of his life.

Grandpa booby-traps his room at the nursing home, always talks about “Nam” and is as hilariously colorful as the Great Jeremy Irons can make him.

“If you must come to tomorrow, I need a flash light, concertina wire and buckshot!”

“You gonna honor our deal? I take care’a you, when the time’s right, you take care’a me. Bullet, straight to the head.”

Grandpa has a Kentucky drawl and cancer, and when the kids come by, he’s perfectly willing to head off to Montana on Harley’s crazy quest to find “the one who got away.”

“She’ll be old, now. Probably smells like cat piss…I walked on a taut 17 year old. What’m I gonna do with a saggy 65?”

Harley is a shy romantic and was hoping to take Steph to the Fireman’s Dance in town that night, but things didn’t work out. His crush may be unrequited.

“I’m all about havin’ babies, and I just don’t think you’re daddy material.”

Still, hope springs eternal. Many a romance blossoms on the road and the road, as the song says, “goes on forever.”

The roadside attractions Harley is hellbent on visiting are more often shown, not identified. So hats off to director Brett Simon, driving that battered minivan past the missile defense pyramid in Nekoma, North Dakota, what looks like Paul Bunyan Land in Brainerd, Minnesota, some woodlands dinosaur attraction (Va., maybe? Florida?), Devils Tower, Wyoming from “Close Encounters,” “Sleep in a Wigwam” motels and the like.

They pick up Fitz, a colorful con man played by Edi Gathegi (“X-Men: First Class”) who seems to “find” whatever they need on their journey.

“I didn’t find them, they found me.”

He dances some Girl Scouts out of their cookies, “You steal?”

“Did Robin Hood steal bread? Did Jesus steal the Grace of God?”

He’s an anti-capitalist philosopher, and he isn’t the only pontificator in this picture. Grandpa’s  “My brother went to Canada, got by brainwashed by felatio, flower power and folk music” outbursts are mirrored by the trigger-happy, racist FBI agent (Maria Bello) on their trail.

“A cost of a year incarceration? $50,000. Cost of a bullet? Fifty cents. Do the math.”

Harley running over a flea market “mall cop” in a getaway gets her juices going.

“Hallelujah! We got ourselves a cop killer!”

“Ma’am, he’s not dead.”

“Come on, now. Gotta think POSITIVE!”

“Better Start Running” reaches for “Forrest Gump” cute, and teeters into sentiment. It’s plotted like farce but plays like something sharper, wittier and quotable — if slower.

Irons is worth the price of admission, all by his High Lonesome self. No, the accent isn’t bullet-proof, but his gruff charm shines through scene after scene, even when there are shots fired.

“Hoo-Hah, we’re talkin’ DIRTY now!”

The leads are more tolerable than engaging, but some scenes sing, the roadside stops have a timeworn charm and Irons, Gathegi and Bello make “Better Start Running” move right along, even if it rarely achieves a sprint.

MPAA Rating: unrated, violence, sexual assault, profanity

Cast: Analeigh Tipton, Maria Bello, Jeremy Irons, Alex Sharp, Jane Seymour, Ed Gathegi

Credits: Directed by Brett Simon, script by Chad Faust, Annie Burgstede. A Freestyle release.

Running time: 1:32