One of the most powerful weapons in a magician's arsenal is misdirection. In fact, the only thing that helps a magician get away with trickery more than a good bit of misdirection is an audience that's been drinking heavily.
For example, let's say that the magician is performing an escape in which he is manacled naked to a chair, doused in gasoline, and set on fire, and has to free himself before he can jump into a nearby pool of water. Let's also say that, in order to escape, the magician needs to grab a key hidden on a nearby table and use it to unlock the shackles, and that he has to do it in a fraction of a second to avoid being burned alive. Well, the magician doesn't want anyone to see him get the key because that would ruin the magic of the moment. So what the magician does is arrange with an assistant (a lovely young woman who is clearly 9 months pregnant) to stand on the far side of the stage and, as soon as the magician is set on fire, put her hand on her belly and make a worried look. The audience will, of course, have sympathy for the pregnant assistant and, seeing that she's concerned that her baby might be ready to arrive, will be concentrating on her instead of on the burning magician. This gives the magician plenty of time to fumble for the key through screams of agony with nobody the wiser.
Misdirection comes in many shapes and forms. It can be a "mistakenly" open fly, the sudden violent illness of someone in the audience, or a gunshot from the theater's Presidential booth. It can even be an "accidental" dropping of a deck of cards and subsequent "ruining" of a trick that wasn't going to work out anyway.
One of the most common bits of misdirection is a shapely assistant in a revealing costume. There's a saying amongst magicians that the less an assistant is wearing, the more you can get away with. The problem with relying on this saying is that it can lead to overconfidence on the part of the magician. This is why it's not uncommon after a late-night Las Vegas magic show in which gorgeous assistants are completely topless to hear a man say something like, "Wow -- did you see how he made that rabbit appear out of that chest?" To which his wife responds, "What are you talking about? It was a hat and the rabbit was in it the whole time."