During the filming of a strip sequence, Gerard Butler's suspenders hit Hilary Swank on the forehead. She received a cut and had to be brought to a hospital where she received several stitches.
According to the Christmas 2006 issue of People magazine, Jeffrey Dean Morgan had to learn to play the guitar for his part in this film in a very short time. His guitar instructor was Nancy Wilson of the band Heart. Morgan was thrilled to take lessons from her because, in his own words, "I had such a crush on her as a kid."
When Holly Kennedy, played by Hilary Swank, tries to choose between different job options, one of them is vampire slayer. Another character in this movie, John McCarthy, is played by James Marsters, who portrays the famous vampire Spike in "Buffy the Vampire Slayer" (1997). Hilary Swank also played in the original film of Buffy the Vampire Slayer (1992).