or: LOOK AT MY PLOT HOLES LOOK AT MY PLOT HOLES!
As a writer, the worst thing you can do is assume that your reader is stupid, lazy, or not paying attention.
This is not because your reader is your friend and you should treat him kindly.
Your reader is your enemy, and he is cunning. He will find your faults and exploit them. He will question your wisdom and second-guess your choices.
You must respect your enemies.
Your job as a writer is thus to create a trap that the enemy cannot escape.
You must create a story your enemy cannot discount or put down.
Of course, this is easier said than done. In addition to the difficulties of creating engaging characters and a memorable world and consistently using compelling word choice, you must also be a master of plot.
But being a master of plot is hard.
At times, it can seem impossibly hard. Sometimes you write yourself into a corner. Sometimes you realize you've made assumptions nobody else would make or can necessarily follow. Sometimes you need the impossible to happen in order to ensure the most mundane of actions in your story can occur as well.
At these times, it can be tempting to treat your enemy as if he is your lesser, to skip over plot holes, to gloss over fabrications.
Don't.
There's an easier solution.
When you've lost all hope of making a plot point work, instead of ignoring your failure and hoping the reader doesn't notice, or plastering over it with something vaguely nonsensical, point it out.
Say to your audience, within the context of the story, Hey, I got a plot hole over here!
Now I know a lot of you are thinking I'm nuts right here -- why would you ever point out your own flaws if there's a possibility others might not notice??? -- but hear me out on this.
Let's say you're writing, say,
2012 (coming soon to a theater near you!). Now, if you've seen any commercials or trailers for this particular film, you're well aware that it's not going to make much sense. It just isn't and it's probably not meant to. The premise is thus: the ancient Mayans predicted centuries ago that the world would end in the year 2012. They were right.
You can make an almost infinite number of stories based on this simple premise, but let's draw attention to just a couple. What we're looking for here is how we would address the practicalities of why the world is ending in 2012 and how the Mayans knew about it.
1. Don't Address The Problem

You can have your main character be an expert in the ancient Mayans who discovers additional evidence that the world is coming to an end, warns everybody, is assumed to be a nutcase, is proven right, and then haves to save the day (most likely by rescuing a family member or a distanced lover).
In this version, you don't really address
why the world is ending in 2012, other than that the Mayans predicted it. You might toss out some panicking scientists who question aloud why it's happening, but without an answer. The Mayans are just right, because they're, like, good with calendars and stuff.
(note: this is more or less the plot of
The Day After Tomorrow
)
The benefit of this strategy is that you don't waste much time on exposition, since there is nothing to expound upon. The negative is that your audience spends the entire time disconnected with your story because you've decided to make it inchoate.
Though I've watched The Day After Tomorrow over 10 times and never fail to laugh uncontrollably the entire time, I am in general not a big fan of this approach.
2. Overly Complicate The Problem
Let's say you don't want the world to just end without a clear cause. How do you get every element of the earth's environment to turn on itself? What could possibly cause this
The answer: aliens.
The Mayans knew the end of the world was coming because the aliens, who control and monitor the earth and always have, told them that 2012 was the end of their experiment. Now your hero, after everybody realizes he's been correct all along, must battle a bunch of aliens to save mankind.
Now, this of course creates its own series of problems. Why did the aliens tell the Mayans anything? What's their purpose in controlling earth and in destroying it? (Maybe they've just been planning on building an
interstellar highway
through our solar system and the Mayans were just the ones who signed off on the eminent domain notice.)
Unfortunately, when you overly complicate something, you have a lot more information that needs to be conveyed for your audience to buy into it. This is the type of situation where you end up with long speeches that bore your audience and make them wish you spent more time blowing $^&+ up.
(note: this is more or less how the
The Matrix sequels
work)
The benefit of this approach is that it creates clear goals for your protagonist and immediately suggests at least one additional set piece and several plot points that you'll need to complete your story.
But it also creates even more believability issues than you started out with.
3. Embrace The Problem
Maybe aliens are a little too much for you, but no other solution is coming to you. You don't want to be too expostion-y, but nor do you want to continue on as if everything is business as usual when clearly it's not.
Hey, remember those panicking scientists that were questioning what's going on? Let's spend a little more time with them. Or, alternatively, why don't we make their questions a central pursuit for our hero?
You see, when the end of the world comes, people are going to be doing some soul searching. Did we create this problem? What could we have done to change the course of events? What does it mean that human kind has known its end date for centuries and yet has behaved as if it weren't approaching? Will they still show the next season of Shot at Love with Tila Tequila?
This isn't a problem, this is an
opportunity.
This works for small problems as well as big. The end of the world is obviously big. But how your character drove across Los Angeles in under 20 minutes is small.
"That's the fastest I've ever driven!" -- problem solved. Hell, you should probably start his drive by acknowledged he only has 20 minutes to do what's normally a 35 minute drive.
What you shouldn't do is just have him make it. Or have him suddenly use those rocket boosters that have been sitting in his car unnoticed.
If your supervillain's superweapon isn't based on your advanced knowledge of physics, it's okay to have a character say, "I don't know how it works, but I know it's deadly."
Not sure your character would know how to operate a gun if handed one? "I didn't know I'd be this good!" Also feel free to make her miss every target and see what happens.

Obviously there's a subtlety needed in most of the actual writing situations you'll face that isn't represented here (or unsubtlety if you're writing a comedy and looking for a laugh). But as long as you're not stretching it to the point of absurdity or just being lazy, you can get away with a lot.
This isn't to say you never need to explain anything. The
DeLorean still needed the flux capacitor, after all, since that was the central premise of the film -- but nobody had to explain how a flux capacitor actually works. Superman can fly because the sun gives him powers, but you don't need to get into why.
The Force just is. When you're dealing with creating an entirely new concept of reality, lip service has to be paid to why it is how it is, but the nitty gritty can be left to the imagination.
Your reader, though cunning, is also forgiving. You get a surprising amount of leeway as long as you're honest. If you try to bull$#!+ your way through your story or try to get one over on your reader, you're going to get called out on it.
But if you ask for suspension of disbelief, you'll be granted it.
Because your enemy respects you too.
Top photo by Sea of Legs (Flickr Creative Commons)
Available here.
Middle photo by extranoise (Flickr Creative Commons)
Available here.
Bottom photo by KirrilyRobert (Flickr Creative Commons)
Available here.