The document discusses 5 common physical data modeling mistakes that can negatively impact performance, development timelines, and cause bugs. These include: 1) Assuming that numbers will always be numeric, 2) Choosing the wrong primary key, 3) Incorrectly applying surrogate keys, 4) Turning off referential integrity for development, and 5) Relying on default settings rather than customizing the physical model. The presentation provides tips on how to identify and avoid these mistakes such as establishing primary key standards, using the correct data types, and testing physical models in a separate database before implementing.