A lot of the deleted scenes on the Director's Cut reveal Elektra's backstory from her childhood.
Also one where she has a rather steamy dream involving her ex, Matt Murdock.
Executive Meddling: The original cut was rated R but had to be toned down due to contractual obligations.
Franchise Killer: Daredevil put it on life support, Elektra put a firm-sai-into-the-gut into the franchise, for lack of a better analogy. The rights reverted back to Marvel within 7 years and they negated the continuity of the movies.
Genre-Killer: The failure of this and Catwoman put an end to female-led action movies for several years, until The Hunger Games and Divergent franchises came along. It's widely thought that this is the reason Black Widow did not get a solo movie in the Marvel Cinematic Universe, as well as other female superheroes having to be introduced as secondary characters in other movies. It took the DCEU's Wonder Woman to eventually prove that a female-led superhero movie can succeed critically and financially.
Lying Creator: Promotional materials claimed that the film had ties to the X-Men Film Series, as they were more popular than the Daredevil film. They only mentioned it as actually being only a Daredevil spin-off a week before its release.
Missing Trailer Scene: Trailers and TV spots show a ring of energy spreading out from the maze in the final action scenes. It does not show up in the final film.
Real Life Writes the Plot: Elektra does not wear her hoop earrings from the comics, because Jennifer Garner did not have pierced ears.
Star-Derailing Role: This film did some damage to Jennifer Garner's career, not helping matters was Alias ending around the same time. She found herself in supporting roles and very few leading parts, and those that she did headline were not big enough hits to change her momentum. While she's had some well-received roles, she has yet to regain the former prominence she had.
The comic book character:
Elektra's initial appearance was based on Lisa Lyon, a female bodybuilding pioneer.