- Awesome, Dear Boy: Sara Paxton lobbied hard for the role of Aquamarine because she is a huge mermaid lover in real life.
- Blooper: In the bike riding scene, Emma Roberts didn't know how to drive with another person sitting on the handlebars. Sara Paxton actually did fall off.
- California Doubling: While the plot involves Hailey moving from Florida to Australia, the film was shot in Australia.
- The Cast Showoff: Two of the three leads sing on the soundtrack (see also Irony as She Is Cast below).
- Doing It for the Art: Sara Paxton threw herself into preparation for the role, taking a month of intensive swimming lessons and living off sardines (feeling that as a mermaid, that would be what Aquamarine lives off). It would take four hours for hair and make-up to be done whenever she had to be in the tail, which weighed about 100 lbs, and she had to be carried in a stretcher while wearing it. Achieving that Godiva Hair effect was not easy either; many takes had to be redone with the hair glued in place.
- Fake American: As the film was filmed in Australia, except for Sara Paxton, Emma Roberts, Jojo Levesque, Arielle Kebbel and Jake McDorman, the entire cast is Australian (and in the case of Shaun Micallef, as Cecilia's father, it shows).
- Irony as She Is Cast: Jojo Levesque plays the best friend to a girl with a fear of swimming. She filmed a scene where she swims with dolphins - and it was she who was afraid. Likewise she's the professional singer out of the three leads and is the only one of them not to sing on the film's soundtrack.
- Unintentional Period Piece: The film is dated to the mid-2000s by some of the technology used; Claire and Hailey call Raymond using a landline phone, the internet is barely used and there's a notable lack of cell phones among the teenage characters. Claire and Hailey's angst about being separated by one of them moving to Australia would be considered much more so in the days before social media (which of course is not mentioned). The crimped hair, Bermuda shorts and soundtrack featuring Mandy Moore and The Jonas Brothers adds to the 2000s setting.
- What Could Have Been: The first choice for Aquamarine was Jessica Simpson, who was unavailable. Likewise Sara Paxton was asked to read for Cecilia, but she lobbied hard to be Aqua.
Trivia / Aquamarine