http://io9.com/10-things-you-probably-didnt-know-about-star-wars-ret-1383276948/1388764126/@jesusdiaz
George Lucas originally planned to have Luke Skywalker to become Darth Vader. His line were supposed to be "Now I am Vader. Now I will go and kill the Rebel fleet and I will rule the universe." Watching Star Wars now you know that is not what happened.

http://www.virginmedia.com/movies/features/20-things-you-never-knew-about-star-wars.php?page=3

The lightsaber sound effect was discovered by accident. You would never think that the sound effect for the lightsaber is made by a microphone passing a muted TV. This caused a low humming sound. He then mixed this with the sound of a film projector, and then the sound of the lightsaber was born.

http://starwars.wikia.com/wiki/Yoda
It seems every Jedi has two names. There is Luke Skywalker, Qui-Gon Jinn, Mace Windu, Anakin Skywalker, and many others, but Yoda does not. In fact Yoda is not his first name. It is actually Minch. His first name is left out on purpose to make the mysteriousness of him that much greater.

http://www.dailyrandomfacts.com/wtf-facts/10-cool-random-star-wars-facts/attachment/star-wars-facts-9/
Before coming a comic relief, Jar Jar Binks was planned to be treacherous mercenary who would eventually betray Qui-Gon Jinn.

http://www.dailyrandomfacts.com/wtf-facts/10-cool-random-star-wars-facts/attachment/star-wars-facts-7/
R2D2 was supposed to be played by a dwarf, but after 3 got to hot while rehearsing they agreed to use a midget. The main difference between the two is that the midget is more resistant to heat.

http://www.dailyrandomfacts.com/wtf-facts/10-cool-random-star-wars-facts/attachment/star-wars-facts-5/
Only George Lucas knew about the famous line "Luke. I am your father!" What most people don't know is that it was originally supposed to be "Luke. Your are your own father!" The reason he changed it was because it really confused and outraged the actors.

http://www.dailyrandomfacts.com/wtf-facts/10-cool-random-star-wars-facts/attachment/star-wars-facts-1/

Originally George Lucas planned on having "A long, long time ago in a not to distant future" instead of "A long, long time ago in a galaxy far, far away." Someone then pointed out to George that it made absolutely no sense.