Several actors in this show made brief appearances in H2O: Just Add Water (2006) including Gemma Forsyth, Lucy Fry, and Dominic Deutscher.
During the casting process for the first season, 500 actresses auditioned for the three mermaid leads. The roles eventually went to Lucy Fry, Ivy Latimer, and Amy Ruffle.
Due a mess up with licenses the second half of season 2 has been added to Netflix as season 3.
In the series finale of H2O: Just Add Water (2006), at the graduation ceremony, right before they call Bella onto the stage, they call forth Lucy Fry (played by Lucy Fry).
Sirena's sister is named Aquata. One of Ariel's sisters in The Little Mermaid (1989) had the same name.