During 2012, the accountant discovered that the physical inventory at the end of 2011 had been understated

Question:

During 2012, the accountant discovered that the physical inventory at the end of 2011 had been understated by $18,000. Instead of correcting the error, however, the accountant assumed that an $18,000 overstatement of the physical inventor in 2012 would balance out the error.
Are there any flaws in the accountant’s assumption? Explain.