A powerful way to understand where gaps are in the expertise of embedded system designers is to look at what goes wrong in real industry projects. This paper summarizes the "red flag" issues found in approximately 90 design reviews of embedded system products conducted over a ten year period across a variety of embedded system industries. The problems found can be roughly categorized into the areas of process, requirements, architecture, design, implementation, verification/validation, dependability, project management, and people. A few problem areas, such as watchdog timers and real time scheduling, are standard embedded education topics. But many areas, such as peer reviews, requirements, SQA, and user interface design seem worthy of increased attention in texts and education programs.