When Big Rick Wolf is talking to Erin at the hospital, his son is standing behind him. In the next shot, the son disappears and then reappears in the very next shot after that.
It's a common mistake made in film and television to say a person found dead on their arrival is DOA. But in actuality, DOA means a patient was dead on arrival at the hospital. It goes way back. And originates from the rules that a patient needed to be pronounced by a physician. Today the term still applies to a dead person arriving at a hospital.
Today, with paramedics being given the power to declare a person dead, "Dead on the scene" is used to describe a person found dead outside a hospital. And this is because DOS is classification that denotes a scene that needs a coroner, not a ride in an ambulance.