I thought this was funny. I am glad Jeopardy sparked me to educate myself a little more today!
1. The Empire Strikes Back (1980)
Misquote: "Luke, I am your father."
Actual quote: "No. I am your father."
Your bête noire, spoken during Luke's illusion-shattering confrontation with his nemesis, Darth Vader, is a perfect example. The pertinent part of the exchange goes like this:
Darth Vader: "If you only knew the power of the dark side. Obi-Wan never told you what happened to your father."
Luke: "He told me enough! He told me you killed him."
Darth Vader: "No. I am your father."
Wow — great moment. But as beautifully as "No. I am your father," plays in context, it's not a one-liner without the specificity of Luke's name. So people remember it as "Luke, I am your father."
2. Dirty Harry (1971)
Misquote: "Do you feel lucky, punk?"
Actual quote: "Ah, I know what you're thinking, punk. You're thinking, 'Did he fire six shots or only five?' Well, to tell you the truth, I've forgotten myself in all this excitement. But being as this is a .44 Magnum, the most powerful handgun in the world, and would blow your head clean off, you've got to ask yourself one question: 'Do I feel lucky?' Well, do ya punk?"
Clint Eastwood sells the hell out of that speech, but the misquoter boils it down to five key words that never occur together.