- The director chose to use a real cable car instead of a prop cable car. So when the realtor follows David across the street to Elizabeth's apartment, she runs across the tracks in her heels to avoid the cable car.
- Co-writer Leslie Dixon suggested using the apartment where she used to live for shooting. She also suggested 'Jon Heder (I)' for the role of Darryl. Both of these suggestions were taken.
- After a bad take while shooting, Mark Ruffalo jokingly jumped out of a window on the set. He landed on a catwalk just outside the window, but still scared the crew.
- The producers bought the rights to the novel without having read the original French book after receiving a proposal with a rough outline of the story.
- During some scenes and rehearsals, the director had Ruffalo wear an earpiece to receive his lines from Witherspoon who was not on the set, replicating the situation depicted in the film, where David has to relay Elizabeth's messages to the others who cannot see or hear her.
- Except for about five days of photography, Reese Witherspoon was in the same outfit (red shirt, black suit) for the entire shoot.
- According to the DVD commentary, Elizabeth's apartment rooftop was completely built on stage with CGI for the San Francisco skyline.
- The wedding video David is watching when he first encounters Elizabeth is actually that of an assistant of one of the film makers.
- When Elizabeth asks David who about the girl that Daryl told him he had to let go of, David responds that her name was Laura. Reese Witherspoon's real first name is Laura and her full name is Laura Jeanne Reese Witherspoon.
- David and Elizabeth’s Apartment building it really about 6 stories tall but the view from the roof (done with CGI) is one from a much taller building. We look down upon other buildings that are of a similar height.
>>> WARNING: Here Be Spoilers <<<
Trivia items below here contain information that may give away important plot points. You may not want to read any further if you've not already seen this title.
- SPOILER: When Elizabeth and David first visit the comatose Elizabeth, Reese Witherspoon most of the time played Elizabeth 'the ghost' and her body double (who looks so like the actress that some people had mistaken her for Witherspoon) was on the bed.
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