Highman runs into Ethan Tremblay, played by Zach Galifianakis, as he attempts to make it to his wife's side for the delivery of their child. Actually, Tremblay quite literally runs into the car door of the limousine in which Highman is riding as he pulls up to the airport curb to catch a flight to L.A. Needless to say, they do not get off on the right foot. To make matters worse for Highman, Tremblay is on the same flight. Before the plane can take off, however, Tremblay manages to get both himself and Highman kicked off the plane and put on the No Fly List. As Highman attempts to rent a car, he discovers to his horror that his wallet is on the plane. Who should pull up but Tremblay, offering a cross-country ride to L.A. Much to Highman's chagrin, he realizes that he is to be stuck with Tremblay in a car racing from the Southeast to Los Angeles, hopefully in time for his child's delivery.
Downey is the straight man in this buddy comedy and Galifianakis is, well, Galifianakis. He is more like a force of nature than a character. Galifianakis has plied his trade so well as the idiot savant that I'm not sure if the breathtakingly oblivious, borderline autistic force of nature that is Ethan Tremblay is the character Tremblay or just Galifianakis. Downey does just as well as Highman with his trademark straight-faced, sarcastic delivery. He is as good a straight man as Galifianakis is a funny man.
The failures of Due Date cannot be laid at the feet of the on-camera talent. On the contrary, they are the primary reason that the film succeeds in culling laughs. And there are plenty of them, to be sure.
The primary faults of the movie lie in its writing and direction. Some moments fall flat not because of the actors, but because of the editing and camera work. Due Date also devolves into a black hole of crassness and banality at one point that is simply disgusting. Some might argue that the implied incident of self abuse, which takes place in a car, is necessary to justify Highman's ditching of Tremblay without warning, in Tremblay's own rental car no less. Nevertheless, the film makers should have been more creative in imagining what the straw could be that finally breaks Highman's patience. Tremblay should be, and for the most part is, a lovably naÏve innocent. Implying Tremblay's self abuse while sleeping in the same car as Highman is not only tasteless, but it vaults the character to a whole new level of dim-wit that I am not sure the filmmakers intended. It felt as though the filmmakers thought the moment would be funny. Not only was it not funny, it did not even fit with the overall character. Even the most mentally challenged understand some boundaries.
Add to that an over abundance of foul language, and Due Date unnecessarily crosses the line. Which is too bad, considering the potential of the film suggested by its funnier and more heart-warming moments.