Trivia: The film was written by Diane Thomas. Thomas was a struggling waitress and actress, and had been working odd jobs to make ends meet when she wrote the script. While there is some dispute over how it happened, eventually the script made its way to actor Michael Douglas, who championed Thomas and helped get the movie made. The script was so well-liked, she ended up getting numerous offers, and at one point was even attached to help write one of the "Indiana Jones" sequels. Sadly, she was killed in a car accident only a year after this movie's release, and it remains the only film she was credited for writing.
Trivia: The studio was so sure the film would be a flop, they preemptively fired director Robert Zemekis from his next project, "Cocoon," and instead gave the job to Ron Howard. Ironically, the film ended up being one of the top-ten grossing films of the year.
Chosen answer: She's lost in Columbia and doesn't have access to money beyond what she has with her. She doesn't want to give him everything she has because she doesn't know when she'll be able to get more.