I can just about guarantee you that you’ve seen Due Date before. I mean, the point of a new comedy is to provide semi-unique situations in which the funniness may flower, so you haven’t seen precisely the same movie as Due Date before (unless you have, and it was named Due Date, in which case that’s what I’m talking about right now, so you see). But you’ve seen Planes, Trains and Automobiles. Or, if not that, you’ve seen the Odd Couple, and putting it in a car really doesn’t change the fact that these guys are polar opposite who hate each other a little bit, and yet there are Circumstances that force them to Figure It Out, one way or another. And man, even if you haven’t seen those, you’ve seen Sesame Street. So don’t try to pretend this movie has a new premise. It just doesn’t.
Not that there’s anything wrong with that. At least, not as long as your movie is extremely funny or has extremely strong actors to carry the conflict on their backs. Because, really, I think the next genuinely new comedy I see will be the first one that anybody has seen in probably centuries and possibly millennia.
 This one wasn’t, although it was funny. But there’ve been enough amazing comedies in the last couple of years that I’m both sated and jaded, and therefore more than willing to call out the difference between ‘I laughed’ and ‘I laughed until I was hurting’.
 This one did. I will I think never get tired of watching Robert Downey Jr. do anything, and Zack Galifianakis, for all that he is not the straight man of the pair, manages to pull off an incredible and limitless flow of dignity through every obscene, absurd, and insane situation that the two of them encounters, and believe me, these are many and varied. But we already have established that you knew that part, having seen this movie-or-possibly-skit-on-Sesame-Street before.