Planes, Trains & Automobiles, is privileged in a number of ways: the first movie he directed that wasn't about suburban teenagers, the only film he directed that was rated R (and, in point of fact, the last film he was involved with in any way that was rated R until 1998's Reach the Rock, which I imagine you, like myself, have never heard of), the first movie he made with his soon-to-be major collaborator John Candy, barring a cameo in the Hughes-scripted Vacation. That last point is almost certainly a mere coincidence, but in its accidental way, it's quite appropriate, for PT&A is effectively the inverse of Vacation: the misadventures of a regular American male having an impossibly bad time getting home, instead of getting to a faraway destination.
In fact, PT&A is probably more like Vacation than it is to any other film Hughes wrote; notwithstanding his debut hackwork on Class Reunion, he was not given to lewd farces, as both of these movies are (they both of them include as one of their finest moments a scene in which the protagonist launches into a genuinely angry comic rant marked by a firestorm of F-bombs), and though there is a certain level of slapstick absurdity in many of his comedies (far more after our current vantage point of 1987 than prior, it must be said), nothing else in his career suggests, quite like these two movies do, that the universe has it out for our lead character personally, and will bend all its will to wrecking his life; simple human incompetence just doesn't cover the extremities suffered by these men.* PT&A is a bit more warm and forgiving in the end, but that's in comparison to what was probably the most savagely anarchic screenplay he'd ever written; beyond a shadow of a doubt, it is the harshest movie he directed, and that is very probably why it is the most funny. At least, it will be the official position of this review that it's his most funny film, with all the usual caveats about "what's funny, anyway?"
As is typical of a Hughes script, the scenario is pretty basic: Neal Page (Steve Martin) is in New York on the Tuesday before Thanksgiving on business, and he needs to get home. First his cab is stolen by a portly man with a pencil moustache, and then his plane ends up being delayed anyway, and he ends up being seated next to the exact same portly man, a traveling shower curtain ring salesman named Del Griffith (Candy), the plane is detoured to Wichita on account of terrible storms at O'Hare (I don't remember the weather in the '80s all that well, but I certainly don't think Chicago has ever had quite the snow accumulation in late November that Hughes depicts here), and before all is said and done, Neal and Del end up roadtripping together while the entire world falls down around them: train delays, problems with rental cars (triggering the exquisitely foul tirade that was one of the main reasons Martin wanted to do the script, while also giving the world a chance to hear Edie McClurg say "fuck" in her instantly-recognisable chipper tones), two horrible nights in seedy motels, stolen money, and the odd car fire.
A comedy theorist could go around and around on why, exactly, the film works - I am tempted to anoint it as the finest comedy screenplay Hughes ever wrote, escalating the various indignities from annoyances to actual life-threatening crises and back down as a reflection of Neal's sense of impatience from moment to moment, and while the dialogue isn't quite as witty as the best lines in Vacation, it's generally tighter and more pointed - but any consideration of that topic really needs to start with Candy and Martin, both of them at the top of their game, and blessed with the most perfect sort of comic chemistry. Subtle the film ain't, but the two actors absolutely never, ever mug for attention: they play the small moments small, and the big moments not too big - again with Martin's "fuck" diatribe, but part of what makes it so great is that the actor plays it stealthily, almost like a predator slashing out with each "fuck" like a sharpened claw; he does not turn it into a big screaming blustering moment as the script could easily have supported and as e.g. Chevy Chase probably would have done.
Between the two of them the actors even manage to put over the sticky-sweet humanism of the piece; no small feat, either. Sentiment was never far away in any Hughes-scripted venture, but he generally let it out more in the films he directed, and it is not typically the case that comedy which depends as heavily upon the suffering of the main characters as PT&A does can withstand all that much sentiment - if we get to liking the protagonists too much, we'll have a harder time watching them in painful situations. I'm inclined to call this the single greatest flaw of the movie (it shares that, in fact, with Ferris Bueller's Day Off, the only Hughes film as writer or director I'm inclined to say I like better than this one: both are at their worst in their most character-driven, sympathetic moments), but the two actors ground Hughes's sensibility in something restrained enough, and critically, adult enough, that it plays alright - Candy in particular doing a fantastic job of it, showing just enough hurt that we can tell he's not entirely the clown that he's set up to be, so when things turn toward the maudlin, it's not quite so jarring and ineffective.
There are, I suppose, moments that don't work - the film's most famous scene, a jolly bit of gay panic triggered by the beloved line "Those aren't pillows", strikes me as far too crude, and so does the rest of the intermittent gross-out humor, and somewhere along the line, the episodic nature of the plot starts to feel a bit too schematic (but then, has ever a travelogue really avoided feeling at least slightly schematic?). But they're only moments. Mostly, the film's simplicity carries it through: though the "mismatched guys getting into scrapes" scenario is old enough to predate cinema, one of the reasons it's such a cliché is that when it works well, it works well, and that part of the movie had been taken care of by the casting stage. As a director, Hughes mostly just stays out of the way (the ingenuity of Ferris Bueller has already gone away, never to come back), but sometimes that's all it takes; and Planes, Trains & Automobiles is a swift, sometimes delirious comedy that doesn't need to be fussy to be excellent.