Here's a fact that's really going to please the math nerds out there; scarecrow's quest for a brain doesn't end as happily as everybody believes it does. To prove that the new brain is working correctly, the scarecrow quotes Pythagoras's Isosceles Theorem. The only problem is that he gets it wrong.
He starts by stating the theorem applies to an isosceles triangle, when in fact it applies to a right triangle. He follows that up by saying 'the sum of the square roots of any two sides is equal to the square root of the remaining side', but that's not right either. He's actually talking about the sum of the squares as opposed to the square roots, and in an event applies only to the two sides that make up the right angle, not any of the sides inside the triangle. We bet he felt really stupid when someone pointed that out to him.