Sofia Coppola wasn't sure if Bill Murray was actually going to show up for the film. Murray works without a management, and according to Coppola, he had only given her a verbal confirmation. While production was being set up in Tokyo with no sign of him, she started to get nervous, but was assured by Wes Anderson (who had directed Murray in Rushmore (1998) and The Royal Tenenbaums (2001)) that Murray was a man of his word. It was indeed when Murray landed in Tokyo one week before filming that his participation was ensured.
Sofia Coppola wrote the lead role specifically for Bill Murray, and later said that if Murray turned it down, she wouldn't have done the movie.
Francis Ford Coppola, Sofia Coppola's father, urged her to shoot the movie in High Definition Video because "it's the future," but she chose film because "film feels more romantic."
The script, which can be found online, wasn't written in the traditional sense, but more in terms of broad scene description that allowed for input by the actors. Many dialogue scenes were heavily improvised, including Bill Murray's lines in the photo shoot and his conversation with Scarlett Johansson about his Shiatsu massage.
Fumihiro Hayashi: as Charlie Brown, the singer of God Save the Queen in the Karaoke scene. Hayashi is Sofia Coppola's long-time friend and guide in Japan.