Following to the repeated observations of leakage and failure-in service of the components manufactured via die casting route, in the stress much lower than their designed an expected level, they were studied and analyzed. Leakage is the sort of defects which frequently has been reported in the high pressure casting components. This study showed that possibility of the formation of air bubbles with and without trails in their wake in the castings is quite high in the high pressure die casting process. It seems that these defects, as special types of discontinuities, have a critical role in the leakage problems and low mechanical properties seen in the high pressure die castings. Bubble damage as frequently seen defects and bubble trail, as a special form of bubble damage defect which already has been reported in the sand casting process, was clearly seen in this study. Specifications of bubble trails observed in this investigation vary to some extent to what already reported in the conventional casting and thus are discussed in this work.