- Awesome, Dear Boy: Poppy Drayton jumped at the chance to play a mermaid.
- California Doubling: Georgia and Florida doubled for Mississippi.
- The Cast Show Off: That is indeed Poppy Drayton singing "When This Story Ends".
- Dyeing for Your Art: Poppy Drayton trained for two months to swim in a monofin and learn to hold her breath underwater.
- Follow the Leader: The Interspecies Romance period piece seems to be taking a few cues from The Shape of Water. The supporting cast also includes a lot of other outcasts from society.
- Playing Against Type: William Moseley often plays royals or action heroes. Here he plays a working class journalist.
- Reality Subtext: Poppy Drayton says that her emotional performance of "When This Story Ends" came from finding out her grandmother had passed away earlier in the day.
- Throw It In!: The sunset in the final scene between Cam and Elizabeth came about because they were trying to hurriedly get the shot done before the sun went down.
- Working Title: 'The Little Mermaid of Mississippi'.
Trivia / The Little Mermaid (2018)