In a plot that feels like it was written with the DVD of Planes, Trains, and Automobiles as guidance, Downey plays Peter Highman, a tense, irritable businessman whose plan to hop on an Atlanta-to-Los Angeles flight in order to catch the birth of his first child is thoroughly derailed by Ethan Tremblay (Galifianakis), a scarf-wearing nimrod whose complete cluelessness accidentally gets the both of them kicked off the plane and slapped onto a "no fly" list. Peter's wallet and ID is with his luggage, and he finds himself with no choice but to pair up with Ethan, who is looking to make amends, on a disastrous cross-country car ride that drains Peter of his limited good nature and sanity.

Galifianakis delivered his Hangover character Alan with a well-timed balance of stupid and spacey, and the result was a scene-stealer. Of course, Hollywood likes one-trick ponies, so Ethan has been fine-tuned to almost the exact same specifications as Alan, except bigger and broader, in a starring capacity. Galifianakis goes through the motions, but he (unsurprisingly) doesn't seem all that invested in repeating himself, lobbing each bit of overly-calculated randomness at the audience with decidedly half-assed enthusiasm. The schtick quickly wears out its welcome when cranked to 11 and given half the available screen time, but the comedian perks up at the script's occasional bit of dramatic substance, and he's actually pretty good, delivering a confession in a dingy rest-stop bathroom and a later sequence involving his father's ashes (carried in a coffee tin borrowed wholesale from The Big Lebowski) with surprising sincerity. Whether the viewer buys it is up to them, but the latter has some surprisingly gorgeous cinematography to add to the bizarre unbalancing act.

Downey's character, meanwhile, is a an angry jerk who does and says more than a handful of things that paint him as an asshole. Phillips doesn't seem to know what to do with him, so I can't claim this magically leads to side-splitting comedy, but I appreciated that he and Downey don't obsess over the audience's sympathy for Peter. Frankly, not only is said sympathy almost inevitable with all the misery Ethan heaps on Peter, but it's just nice to see a mainstream comedy where the filmmakers don't insist on beating around the bush when it comes to someone being forced to deal with a character like Ethan. Again, I admit that the movie doesn't use this as well as it should: Peter never has any sort of epiphany that will help him through the similar struggle of parenthood, nor does he do anything truly and deeply dark, like murder Ethan in cold blood. But most human beings aren't all polished to a fine sheen, and neither is Peter.

Given these elements, the tipping point for most audiences comes about two-thirds of the way through the movie, when the pair accidentally roll up to the US/Mexico border while stoned out of their minds. Some people will be annoyed that the actions Ethan takes to get them out of the situation have no consequences, and it's absolutely true that the pair gets off scot-free, despite a laundry list of reasons someone would be after them and they'd probably both end up in prison. Still, the film not only goes for its jokes, it goes for its jokes without any concern for believability, realism, or the audience's suspension of disbelief, which has to qualify as comedy without a net. Due Date is not a rousing success, and the stream of hatred and anger that spews between the two characters could easily grate on the nerves. But here they are, in all their glory: for better or worse, their personalities, and the film, are without compromise.