Christopher Reeve was originally going to appear in the film, but he bowed out just before filming began.
John Williams' theme for Superman appears briefly in Jerry Goldsmith's score.
Helen Slater had to train three hours a day for three months to do the outdoor flying sequences where she was suspended by wires from a 200ft tower crane.
The town of Midvale was built from scratch on a back lot at Pinewood Studios.
The scenes in which the monster tractor destroys the town took 22 consecutive days to shoot.
The scene where Supergirl flies out of the lake was actually a photograph of Helen Slater pasted on a wooden cut-out.
The footage of the Vortex that appears behind Peter O'Toole and Helen Slater towards the end of the film was filmed underwater.
Behind the scenes footage included on the DVD release reveals a very different costume was planned for Supergirl than the one seen in the film. This costume design was actually based upon the revised costume worn by Supergirl in the DC comic books beginning in the early 1980s. The unused costume included a headband and curly hair amongst other differences.
Almost 85% of the film was shot on giant sound stages at Pinewood Studios.
The film's opening credits cost almost $1 million dollars to shoot.
Several references to Superman as Supergirl's cousin. A poster of Superman is displayed at Supergirl's college room.
Marc McClure also played "Jimmy Olsen" in all 4 Superman films.
Demi Moore was slated to play Lucy Lane, but opted out at the last moment.
There were approximately five script re-writes before filming began. In one version of the script, the film was going to begin with the destruction of Krypton from Superman: The Movie.
Intended to be the first of a series of Supergirl films, but its lack of success at the box office ended these plans.
The original movie poster incorrectly shows the Statue of Liberty holding the torch in her left hand, instead of the right.
The movie was completed by copyright holder Warner Brothers. However, due to the chaos from Superman III (1983), Warners decided to drop the film and keep it on the shelf. Later, the then fledging Tri-Star Pictures decided to pick it up, and cut it down to a viewing time of 105 minutes, from 126.
The dean of the college that Linda Lee attends is named Mr. Danvers. In the Supergirl comics, Linda was adopted by a family named Danvers, and even took on their surname, Linda Lee-Danvers.
Completed its theatrical run in early February 1985. Almost four months later, it reached the home video market for sale and rentals on 30 May 1985. The distributor was U.S.A. Home Video.
Brooke Shields was the first choice for the role of Supergirl, and Christopher Reeve was going to have a substantial role. The original script had Supergirl trying to rescue Superman who had fallen ill due to Selena's magic.
With a total gross of 14 million dollars this movie made the least money of all the films in the Superman series, followed just behind Superman IV: The Quest for Peace which made 15 million. The total budget for Supergirl was 35.
The budget for this film was 50 million dollars, as much as Superman (1978). There was also an additional 10 million worldwide advertising campaign. Even though the film performed poorly in North America, it actually made a lot of money in Europe and in the Asian markets.
Helen Slater's film debut. Many years later, Slater made a cameo appearance in an episode of "Smallville" (2001), playing Lara, the Kryptonian mother of Kal-El/Clark Kent, in a flashback scene and later a clone of Lara.
Dolly Parton was offered $7 million to take the role of Selena, but she turned it down, claiming that she couldn't play a witch, no matter how much money was offered.
Ilya Salkind's partner, Alyssa Cartagena, was the original producer of this film. However, during pre-production and principal photography there was much tension between Cartegena and Alexander Salkind. Cartegena was not pleased with the script or the film's publicity campaign. Eventually she was replaced by Timothy Burrill, the co-producer. Cartegena was very resentful as she had secured a majority of the films financing and was responsible for bringing Faye Dunaway on board.
Melanie Griffith was considered for the role of Supergirl.
Jane Fonda and Goldie Hawn both rejected the role of Selena.