When Jamie Lee Curtis found out that Lindsay Lohan, who was going to be playing her daughter, had starred in The Parent Trap (1998), she asked, "Which twin did she play?", unaware that Lohan had performed both roles.
A member of the band Orgy instructed Jamie Lee Curtis on how to play the guitar. In the concert sequence, although Curtis practiced at making it look authentic, in the finished film a studio musician overdubbed the guitar solo
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.
The snapshots in the opening credits are actually photos of Jamie Lee Curtis and her daughter Annie Guest.
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.
Mark Harmon and Jamie Lee Curtis repeat their roles as lovers eight years later in the ninth season of NCIS (2003), as Special Agent Leroy Jethro Gibbs and Dr. Samantha Ryan.
Michelle Trachtenberg was cast as Anna, but had to back out, due to her contractual obligations to Buffy the Vampire Slayer (1996).
Lizzie McGuire: Those Freaky McGuires (2002), an installment of Lizzie McGuire (2001) (also produced by Disney), is considered a fourth version of Mary Rodgers' story. "McGuire" star Hilary Duff and Lindsay Lohan had a rivalry during this period, and apparently, Duff, losing out on this role, demanded that her show get "Freaky" for one installment.
The cover of Tess Coleman's book, "Through the Looking Glass", is the same cover as the original Freaky Friday novel written by Mary Rodgers.
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 Murray (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. The main character was portrayed by Hillary Duff who lost out on the role of Anna to Lindsay Lohan. The two were in in a very high profile feud at the time.
Annette Bening was originally slated to play Tess Coleman. She backed out shortly before filming, and was replaced by Jamie Lee Curtis. Sigourney Weaver was also considered.
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.
The "S" and "Y" on the Sony television in the teacher's lounge is blacked out, leaving "ON" on the front of the set.
The guitar that Jamie Lee Curtis plays offstage during the show at the House of Blues is an Ernie Ball/MusicMan Steve Lukather (Toto) Signature Model.
There are various F.o.N. posters in the garage. F.o.N. is the band in which Danny Rubin plays.
Julie Gonzalo who plays Anna's archenemy Stacey would later go on to play Jamie Lee Curtis' daughter in Christmas With The Kranks.
Jodie Foster whom played the daughter in the original Freaky Friday (1976) was offered to play the mother but passed.
Despite the fact that this was filmed in the standard spherical format, "Filmed in Panavision" is listed in the end credits.
Marc McClure: Annabelle's love interest (Boris) in Disney's original version of Freaky Friday (1976) as Boris the delivery man.