The Pain in the Heart - S3-E15
Character mistake: Zach, from his hospital bed, says he used 3 grams of the monomer to make the explosion. 3 grams of a powder would be a very small amount; less than a teaspoonful. But when he actually did use it, he took a loose amount in a large tablespoon. Zach would have carefully measured it in order to be precise; but he did not. So this is a factual error in what he says; it is also a character mistake in that Zach is the personification of technical accuracy, and would never take a casual spoonful - especially of an explosive.
Suggested correction: Given subsequent revelations, this could be said to be part of everything that goes on.