Corrected entry: Walter White correctly starts to lose his hair at the beginning of the chemotherapy. The errors occur afterwards (I know this from my own experience): 1. The mustache would fall out as well, 2. Walt has hair stubble throughout the treatment (and even has to shave his head!), while in reality a "chemo-head" is simply bald as a baby face since the hair is gone.
Corrected entry: Walt steals 2 masks from the school lab. When they go cook and Crazy8 and Emilio show up, he kills them with the gas. Because of the fire he puts one of the masks on himself and the other one on Jesse and they drive away with both masks, but the DEA find one of the masks at the cook site.Hmhmh