Computing researchers perform detailed reviews and conduct independent analyses to identify Zero Day Defects in computing solutions and software products, defects that may exist despite the observation that the system is functioning properly and is otherwise producing correct results. This paper demonstrates that the same review and analytical skills used to identify Zero Day Defects in software reveal a Zero Day Defect in Einstein's Special Relativity Theory. Specifically, it places Einstein's expressions and equations into a visual mathematical context that illuminates their relationships and facilitates the unambiguous identification of the defect and its root cause. Like Zero Day software defects, the Special Relativity Zero Day defect only manifests in certain conditions, but otherwise the theory's equations produce good results. This analysis demonstrates the strength and importance of Zero Day Defect analysis to identify previously undetected problems, while simultaneously extending this important computational analysis technique to other scientific disciplines.