Kelly Osbourne originally auditioned as Anna (not as Anna's best friend) and was offered the part but decided to back out. Later, she said people told her it was the biggest mistake she'd ever made, due to the success of the movie.
Producer Andrew Gunn said he initially hoped Jodie Foster, who played the daughter in the original film, Freaky Friday (1976), would be game to play the mother in the remake. Foster declined, in part because of concerns that the casting stunt would overshadow the movie's overall merit.
As a homage to Jamie Lee Curtis's mother Janet Leigh, known for her performance in Psycho (1960), a character named Mr. Bates is present in the film. This is a nod to the character of Norman Bates in Psycho (1960).
Chad Michael Murry (Jake) and Julie Gonzalo (Stacy) later worked together on A Cinderella Story (2004) in similar roles. Murray was again cast as the main character's love interest, while Gonzalo was again cast as the main character's rival.
Lindsay Lohan has starred in a few movies that involve some sort of "swapping". In this movie, her character swaps bodies with their mother. In Just My Luck (2006), her character swaps fortune and luck with a man. In The Parent Trap (1998), she plays both twin sisters, who swap lives, and pretend to be one another.