The scene where Joel and Clementine watch the circus go through the streets was made up on the spot, as the film crew and cast happened to be working nearby and Michel Gondry decided it could work well in the film. The part where Clementine disappears suddenly is one of Gondry’s favorite moments of the film, as Jim Carrey didn’t know Kate Winslet was going to disappear and Gondry liked it because Carrey’s face appears so saddened. When the sound blanks out in the final film, Carrey is actually saying “Kate?”
"That’s Lily all over, you know: she works like a slave preparing the ground and sowing her seeds, but the day she ought to be reaping the harvest, she oversleeps herself or goes off on a picnic”… “Sometimes,” she added, “I think it’s just flightiness, and sometimes I think it’s because, at heart, she despises the things she’s trying for. And it’s the difficulty of deciding that makes her such an interesting study."