In Due Date, Todd Phillips begins with a premise so wrung-out I’m bored recounting it — two viscerally mismatched people thrown together on a desperate road trip — and gives it more zing than it deserves. He does this by sticking to formula beats but pushing the envelope of decency. Another filmmaker might have the uptight straight arrow annoyed by, say, his slobby new companion’s snoring or even flatulence. Here, Peter (Robert Downey Jr.) lies in the back seat of a car and writhes as actor and fount-of-chaos Ethan (Zach Galifianakis) loudly whacks off. The whole thing has the vibe of dirty-minded boys sitting in a room (there are four credited screenwriters) and trying to top one another for tastelessness.
The writers also, in the tradition of John Hughes and earlier Phillips comedies, can’t get enough of homosexual (“bromantic”) panic, which means that Peter must first be grossed-out by Ethan’s hairy, sweaty stomach and crotch as they’re pressed into his face, and later loosened up enough to throw his arms around the man and proclaim his love. Thousands of miles away, in L.A., Peter’s pregnant, about-to-pop wife (Michelle Monaghan) has no idea that she’ll soon be shared by two symbolic papas.
The other thing that puts Due Date over is a general reliance on deadpan. Downey, with his perfect pitch, knows just how slow to burn and when — and how much — to surrender to hysterics. He doesn’t soften his anger: He knows the biggest laughs come when the straight man (think Moe Howard) looks truly capable of murder. Galifianakis is an equally shrewd comic actor. He’s high energy but disarmingly matter-of-fact in his ineptitude. Given to the odd effeminate flounce to express his exquisite dignity, he seems genuinely delusional.
The supporting cast is agreeably camp-free, which means Danny McBride’s Western Union clerk (an Iraqi vet) goes from robotically indifferent to frightening, and Juliette Lewis's slatternly mother and drug dealer is treated with dismaying nonchalance. As a star football player with a suspicious attachment to Monaghan, Jamie Foxx — who made somewhat icky music with Downey as a schizophrenic violinist in The Soloist — must have relished the chance to unnerve his co-star by acting overly, eerily placid.
At journey’s end, though, Due Date is less than exhilarating. It’s still a formula mismatched buddy movie that goes nowhere you haven’t been, happy to hug the Interstate, willfully oblivious to other roads and a more surprising — and even more riotous — world elsewhere.