Factual error: While discussing the death of a car accident victim with detectives, the pathologist Dr Hendricks takes out a french fry, seasons it with mayonnaise and eats it. She is in the morgue, wearing bloodstained scrubs. Nobody ever eats or drinks in a morgue. This is not a character error; eating and drinking in a sterile laboratory environment is absolutely forbidden and this is taught to medical and science students from day one of their degree courses. In fact she would not even have food in there in the first place.
Factual error: Ryan, the laboratory technician, eats his lunch of burger and fries while discussing a murder case with Assistant D.A. Claire Kincaid. Trouble is, they are in his laboratory. No lab technician ever, ever eats or drinks in a laboratory - it is the most basic lab protocol imaginable. He could contaminate his samples in any one of a hundred ways, he inevitably contaminates his gloves or fingers with residue from his meal and he risks poisoning himself with accidental transfer. This is not a character error - lab security is hammered into science students starting with the first day of first year and number one on the list is never, ever eat or drink in your lab.
Factual error: When the cops need to arrest a medical professional, they are frequently shown barging into his/her office, exam room, or even operating room. This would never happen in real life and is strictly forbidden, as it is a gross violation of the patient's privacy, and in the case of the OR, could contaminate the sterile environment, thereby jeopardizing patient safety as well.