Plot hole: When Cleo sprays Zane with the fire hydrant, she unscrews the hydrant's cap. She shouldn't be able to do this because she controls water, not objects.

Other: The girls say they hold their breath underwater for fifteen minutes. Why do they need to hold their breath at all? Aren't they mermaids?

Plot hole: When Emma gets the water bottle out of the fridge, the bottle that she touches is wet, so shouldn't this trigger her transformation?

Factual error: When Emma freezes the water in Elliot's shower, frozen water continues to fall on Elliot. This is not possible because Emma only froze the water Elliot was using. Water would still come out of the shower head, but ice comes out instead. Arguably, Emma could be freezing the water in the pipes, but if she did that, nothing would come out of the shower.

Continuity: In the episode "Pool Party", Lewis cannot lift Cleo in mermaid form because of her weight. But in this episode, the girls are able to push Emma around on a wheelchair in mermaid form without breaking sweat.

Continuity: Near the end of the episode, when Rikki falls over after growing her tail, she falls forward. But, in the next shot, she is lying on the ground face up.