- Ending Fatigue: In Season 1, The climax of Zac getting the trident happens in the eighteenth episode, leading into a cat and mouse game of the girls and Zac fighting over the trident for the next 8 episodes (with a completely unrelated episode to the plot thrown in there for good measure)
- Growing the Beard: Starting in the second season, the protagonist characters start behaving much more kindly toward one another, having fewer and less petty interpersonal conflicts and usually discussing problems at hand politely and with respect to everyone's viewpoints. Contrast with Nixie and Evie getting into a physical fight over shoes...
- Ham and Cheese: The three titular mermaids, particularly Nixie (Ivy Latimer), who takes a bigger slice. Just see them learning to walk in the second episode.
- Heartwarming Moments: When she learns that Zac is her younger brother, Mimmi immediately chooses to interpose herself between him and Veridia in his defence, knowing she'll be banished from the pod for it. More than that, Ondina, who doesn't particularly care for Zac, also protects him out of loyalty to Mimmi.
YMMV / Mako Mermaids: An H2O Adventure