In the script, Solo’s response to Leia’s declaration of love for him was written as “I love you, too.” It’s now lore that Ford changed it to “I know.” But if you read the transcript of Ford’s conversation with Kershner on the set, you can see that Ford wasn’t just being a smartass. He put a lot of thought into that line. “But if she says, ‘I love you,’ and I say, ‘I know,’ it’s beautiful and it’s acceptable and it’s funny,” he pleaded. “The point is, I’m not worried about myself anymore; I’m worried about her.”
I have an urge to go on a huge happy rant about dialogue and how awesome it can be, but instead I’m just going to sigh romantically.