Well, I was in physics yesterday when I thought "You know... technicly almost every answer I've given this year is wrong because it's in 2d."

A good example is gravity, you divide by r^2 (which has to do with the surface area of a sphere). If we're in 2d, we should only divide by r (perimeter of circle) and not divide at all in 1d...

Just struck me as kind of odd. Also means if we were in 4d gravity would be weaker. (divide by r^3)