- The Other Darrin:
- By the time of the film's production, Kenneth Mars was in the early stages of his pancreatic cancer, and he couldn't reprise his role as King Triton. Thus, Jim Cummings replaced him. Mars eventually died on February 12, 2011, over two years after the film's release.
- The voice actresses for Ariel's sisters are all different for this movie and the TV series:
- Attina was voiced by Kath Soucie in the TV series, and by Kari Wahlgren in this movie.
- Alana is voiced by Jennifer Hale instead of Kimmy Robertson.
- Grey DeLisle replaces Caroline Vasicek and Mona Marshall as Aquata. She also replaces Kimmy Robertson and the late Mary Kay Bergman as Arista.
- Tara Strong replaces Sherry Lynn as Adella and Cathy Cavadini as Andrina.
- In the Latin American Spanish dub, Ariel's regular voice actress Cony Madera provided her singing voice instead of Isela Sotelo. Jorge Lapuente also replaces Guillermo Romero as King Triton due to the latter living in Los Angeles.
- Playing Gertrude: Ariel is the youngest of all the sisters even though Jodi Benson (1961) is older than Jennifer Hale (1972), Tara Strong (1973), Grey DeLisle (1973), and Kari Wahlgren (1977).
- You Sound Familiar: Tara Strong, who voiced Ariel's daughter Melody in Return to the Sea, voices Ariel's sisters Adella and Andrina in this film.
Trivia / The Little Mermaid III: Ariel's Beginning