The film features only two characters from the TV series: teenage witch Sabrina Spellman (played by Melissa Joan Hart), and talking cat Salem Saberhagen (voiced by Nick Bakay). Lindsay Sloane was also a regular actress in the TV series, but plays a different character in this film. Tara Charendoff reprises her role as Gwen from Sabrina Goes to Rome. As the film is set in Australia, none of the scenes are filmed on the original set of the TV series.
The film was directed by Kenneth R. Koch, who helped to produce Sabrina Goes to Rome. He also directed many episodes of the television series and was a prominent producer of the show.
Unlike Sabrina Goes to Rome, which is included in the season 7 DVD release of the Sabrina the Teenage Witch TV series, Sabrina Down Under did not receive a DVD release (except in Germany), until it was announced in December 2016, that the film will be released on DVD on February 7, 2017. Prior to this, the film has been released on VHS, and is available to stream on Hulu.
Sabrina travels to Australia's Great Barrier Reef with Gwen, a fellow witch from England, for a week-long vacation where they try to help protect a hidden mermaid colony whose habitat is threatened by ocean pollution, and by local marine biologist Dr. Julian Martin, who is determined to find the colony as his claim to fame. While Sabrina finds a friendship with Barnaby, a "merman" from the mermaid colony, Salem the cat finds a possible romance with another witch-turned-into-a-cat named Hilary, but finds Sabrina's problems interfering with his plans. In order to prevent Julian from launching a search for the mermaid colony, she casts a spell to create a storm to keep him in port, which succeeds except that a lightning bolt knocks Sabrina unconscious, and when she comes to she learns she has lost her powers, at least temporarily.
- Water and sand,
- Land and air,
- Give me a man with legs to spare.
- To Create a Storm
- (Cast by Sabrina Spellman)
- Waves to toss with violent motion,
- Squall upon a tranquil ocean.
- Clouds and rain, thunder and lightning,
- Give me a storm that's truly frightening.
- Melissa Joan Hart as Sabrina Spellman, a teenage witch, visiting Australia to discover the Great Barrier Reef, and meet marine biologist Dr. Julian Martin. She discovers merman Barnaby, who she gives legs when she sees that he is ill.
- Tara Charendoff as Gwen, a British witch whose spells never go the way she plans. She and Sabrina go on holiday to Australia together. Gwen was introduced in Sabrina Goes to Rome.
- Scott Michaelson as Barnaby, a merman who turns into human for 48 hours, thanks to Sabrina's magic.
- Lindsay Sloane as Fin, Barnaby's mermaid sister who initially despises humans.
- Nick Bakay as the voice of Salem Saberhagen, a 500-year-old witch, sentenced to spend 100 years as a cat as punishment for attempting to take over the world. While on his yearly vacation, he is surprised to find Sabrina there. He quickly falls for Hillary who is also a cat, however the two break up when her sentence is up and she is turned back into a woman. While taking a picture he discovered who had been polluting the ocean.
- Peter O'Brien as Dr. Julian Martin, a marine biologist who spends his time protecting the reef.
- Rebecca Gibney as Hilary Hexton, a witch imprisoned in the body of a cat. She begins to date Salem, however when she is turned back into a witch she says goodbye to him.
- Conrad Coleby as Jerome, a boy whom Gwen gets attracted to. He is cute, sweet and funny, but he is often hard to understand due to his use of Australian slang.
- Ben Lawson has a small appearance as an employee of the resort.
- This movie takes place in between the Season 3 finale "The Good, the Bad and the Luau" and the Season 4 premiere "No Place Like Home."
- A novel adaptation of the movie was released in the Sabrina the Teenage Witch novel series. As with the two other "special novels," it is unnumbered.
- The cat and puppet used for Hilary are the same ones used for Juliette Jingleheimer in the season 4 episode "Salem and Juliette."
- Lindsay Sloane (who starred as Valerie Birkhead) portrays the Mermaid Fin, making this the actresses' last appearance in the Sabrina the Teenage Witch franchise.
- This is the final appearance of Gwen.