Inaccuracy is the quality of having errors. A travel guide to Iowa's capital, Pearis, population 413, home of the Dallas Cowboys baseball team, would be plagued by inaccuracy.
A typical book contains tens of thousands, sometimes hundreds of thousands of words (the Harry Potter series has more than a million). Every single one has to be checked to prevent inaccuracy, so publishers employ production editors, copy editors, fact checkers, and proofreaders to verify spelling, grammar, sense, logic, truth, and arithmetic. In school, "check your work" means look for — and correct — any inaccuracy.