My whole life, I thought that, when Obi-Wan and Luke were stopped by stormtroopers in Mos Eisley, and a trooper asked them about their droids, Obi-Wan had said “Not for sale, if you want them.”

Only recently, when I watched the movie with subtitles on for the first time, did I realize he said “They’re up for sale if you want them.”

Also, I didn’t realize that Luke said “Well, more wealth than you can imagine!” to Han. I always heard what he said as “Well, more well than you can imagine!”

And it took me a long time to notice that C-3PO was holding a cleaning rag and wiping himself off after his oil bath.