Nanobots microscopic robots come to Townsville to eat all the carbon in it. The solution is to have the girls shrink to microscopic size to defeat them.
Nano Of the North provides examples of:
- Always a Bigger Fish: The Professor gets to play this role. In the climax, the nanobots combine into a single robot that is many times larger and stronger than the now shrunken girls, but still very tiny and fragile compared to a regular sized adult human. The professor simply flattens him under his foot.
- The End Is Nigh: In the intro, we see a man with a sandwich board reading Dark Days Ahead. When a looming shadow envelopes Townsville, his sign changes to "Told You So."
- The End of the World as We Know It: What Professor Utonium predicts will happen if the nanobots are not stopped.
- Funny Background Event: While the girls are hypnotized by the TV show they are watching, the Professor (whose clothes are being eaten by the nanobots) runs back and forth screaming in the background.
- Grey Goo: The nanobots destroy everything made of carbon, quickly melting away Townsville, and use the material to make more of themselves.
- Hoist by His Own Petard: When trying to take out the girls the nanobots concentrate their entire number into one giant monobot. However through its giant to the girls it's only a few inches tall to the rest of the world, and now that its big enough to see the Professor can easily crush it with his foot.
- If My Calculations Are Correct: Said by Professor Utonium during his brief lecture about the nanobots. And unfortunately for Townsville, his calculations that millions of nanobots are now raining down on the city IS correct.
- Incredible Shrinking Man: In order to fight the nanobots, the Professor shrinks the girls down to their size.
- It Can Think: The nanobots, prior to engaging the shrunken girls in battle, seemed to be mindless drones that only sought to multiply by consuming carbon. But as more and more of them are destroyed by the girls, they divert their attention from consuming Townsville completely in favor of focusing on killing the girls.
- Naked People Are Funny: During their first attempt to fight the nanobots, the girls end up naked since the bots eat away their clothes. Earlier, the Professor also had this happening to him.
- No Ending: Well, the nanobots are still defeated, but episode simply ends while the girls are still shrunk, and Townsville is practically damaged even more than usual.
- Riddle for the Ages: It is never revealed where the nanobots came from.
- Scenery Censor: When the girls return home naked after their first failed attempt to defeat the nanobots, the Professor's arm covers up everything from the front, and Blossom's hair covers up her behind (Bubbles and Buttercup use their hands though.
- Shout-Out: The title is based on Nanook of the North.
- The Spook: We never learn who made the nanobots or where they came from.
- The Worm That Walks, mixed with Combining Mecha: When its clear they are losing to the girls, the remaining nanobots form into one gigantic (compared to the girls anyway) robot.