The movie is essentially Planes, Trains and Automobiles Redux, as two airline passengers -- one gregarious and oblivious, the other preoccupied and uninterested -- have to share a car (okay, a string of cars) for a long trip. But instead of driving from New York to Chicago because a blizzard grounded their flight, they have to drive from Atlanta to Los Angeles because an argument about whether or not it's okay to say "bomb" on a plane got them both booted from said plane and put on the no-fly list. Peter (Robert Downey Jr.) has to get home in time for his wife's scheduled C-section; Ethan (Zach Galifianakis) has to get there for a meeting with an agent, so he can become an actor. But since he's not as pressed for time, he's more willing to take detours to buy medical marijuana, dispose of his father's ashes (in a coffee can, Lebowski-style) and to accidentally almost cross the Mexican border.

Peter doesn't appreciate any of this, of course, but it's only partially because Ethan is annoying. It's also because Peter is kind of a dick. He's rude to pretty much everybody he meets, from his driver to the Air Marshall who shoots him to the TSA agent who grounds him to the Western Union teller who can't help him out. He's terrible with kids, which is indicated early on when he has to watch the children of Ethan's weed dealer (Juliette Lewis); I won't tell you how that adventure ends, but needless to say, you start to worry about him as an imminent father. And Ethan is annoying, sure, but, to be fair, his dad did just die, and the grief he channels when asked to play a scene for Peter is real, and makes us sympathize with him more, even as Peter does his best to make us sympathize less -- although his absentee-father issues come up, as well.

Yes, there are still jokes in the movie that didn't make it into the commercials -- because many of them really couldn't, they were so raunchy. Remember, this is Todd Phillips, the director of Old School and The Hangover -- both films that occasionally cross lines of good taste but rarely deliver solemn moments. This one does both, and has a hilarious running Two and a Half Men gag to boot. You can't really ask for much more than that.

Watch a hilarious interview with Zach Galifianakis and read a candid Q&A with Due Date director Todd Phillips.

Did you see Due Date? Let us know what you thought below, then check out our guide to the greatest road movies! And check out our review of the trailer below!