Central venous catheterization (CVC) is an interventional technique which is frequently used in critical patient care for diagnosis and treatment. As in all interventional procedures, CVC may be associated with both short and long-term complications. Here, we report two cases to demonstrate infrequent, but possible causes of mechanical complications related to CVC. The first case was a 24-year-old man with non-Hodgkin lymphoma who initially underwent femoral vein, then internal jugular vein (IJV) catheterization. A forgotten guide wire extending from the left femoral vein to the right IJV was noticed several days after the femoral venous catheterization during an attempt at an IJV catheterization. In the second case, who was a 71-year-old woman requiring CVC for hemodialysis and monitorization, the tip of a left IJV catheter, inserted after several attempts, was found in the right IJV. These cases illustrate the importance of obtaining and appropriately evaluating radiograms after venous catheterization, while bearing the possible mechanical complications in mind.