In Star Wars: Episode V – The Empire Strikes Back, Princess Leia says to Han Solo, “I love you,” and Han’s response is, “I know.” Both lines varied from the initial script, as it was revealed in J.W. Rinzler’s book The Making of Star Wars: The Empire Strikes Back, via Yahoo! News. Leia’s line was written as, “I love you. I couldn’t tell you before, but it’s true,” while Han’s response was supposed to be, “Just remember that, ‘cause I’ll be back.”
Harrison Ford and director Irvin Kershner had a conversation about the scene, which was recorded on an audio cassette tape and transcribed for the book. During their talk, Harrison suggested the alterations that made the final cut in the film.
“I think she ought to just say, ‘I love you,’ as I’m passing by her,” Harrison said during the discussion, before adding, “If she says, ‘I love you,’ and I say, ‘I know,’ it’s beautiful and it’s acceptable and it’s funny.”
Source: https://www.buzzfeed.com/devinherenda/last-minute-line-changes-in-movies-that-made-a-huge