Time Zones
One imaginary line through the Pacific can put two neighbors on different calendar days at the very same moment.
Climate Zones
Some regions have already slipped from one official climate zone into another, and climatologists track it as a sign of climate change.
Map Projections
The world map hanging in most classrooms makes Greenland look roughly the same size as Africa — in reality, Africa is about 14 times larger.
Biomes
A rainforest in Brazil and a rainforest in Southeast Asia can share almost no species in common, yet ecologists still classify them as the same biome.
Continents & Oceans
A basic geography question, "how many oceans are there?", that doesn't actually have one single universally agreed-upon answer.