'Due Date' past its sell-by date

Ever since his hilarious performance in “The Hangover,” Zach Galifianakis has been on a roll. His YouTube videos have view counts in the millions, various celebrities are lining up to be farce-interviewed on his online show, “Between Two Ferns,” and now he’s made national news by supposedly lighting up a joint on “Real Time with Bill Maher.” So it must have been a no-brainer for producers to green-light “Due Date,” which might have been more aptly titled, “The Hangover 2: Hey Look, More Zach Galifianakis.”

Director Todd Phillips has made a living off his buddy comedies, from “Road Trip” to “Old School” to “Starsky & Hutch” and, of course, “The Hangover.” “Due Date” follows in the tradition of his previous bromances, featuring a road trip, male bonding and much masculine debauchery. And Galifianakis also reprises his tried and true role: the oblivious-yet-loveable goofball.

But every whack job needs a straight man, and in this case it’s Robert Downey Jr. He plays Peter, a high-strung architect traveling home to his wife (Michelle Monaghan) in Los Angeles to witness the birth of his child. Unluckily for him, he boards the same plane as Ethan, a permed, puerile and hip-swaying Galifianakis. What starts innocently enough with Ethan’s hairy potbelly bulging into Peter’s face leads to Peter being shot with a rubber bullet, placed on the no-fly list and left stranded in Atlanta with no wallet and no way of getting home.

Inevitably, Peter and Ethan end up riding together across the country, with all the requisite slapstick mishaps. Cars are flipped, children are punched and fights are picked with people in wheelchairs. There’s also an over-the-top marijuana scene, visual hallucinations and all (with depictions like this, it’s no wonder California’s Proposition 19 failed last week).

The same outrageousness that made “The Hangover” so enjoyable is here; however, the fun and wit are missing.

Peter is simply too unlikeable, which is more of the script’s fault than Downey’s. How can we sympathize with a man who sucker-punches an elementary school kid? Or a guy who spits on a dog’s face? Or whose vitriol toward Ethan — a lonely, boyish man — is at times overly spiteful?

Sure, “Due Date” is sometimes funny, but weirdly so. For example, humor comes at the expense of Ethan’s dead father, whose ashes he carries with him in a coffee tin. Downey and Galifianakis have only passable chemistry together, and most of their banter consists of Ethan using Peter as a foil for his lines, which include more than a few references to masturbation, both human and animal.

The sequence of disjointed events never quite hits the mark, and the comic timing seems to deflate after each scene, anemically resetting itself. We get a disproportionate amount of running time dedicated to car chases and other fillers (Jamie Foxx makes an appearance), which are all passable but nothing special. That’s not to say that “Due Date” is not entertaining — sure, there are laughs to be found. But with a duo like Downey and Galifianakis, you’d expect a little more. Blame the script.