At around 2:13, after speaking of disease, they show a woman wearing an oxygen mask. There is no hose connected to the front revealing there is no need for the mask.
It is not clear how Frank was able to exit the police station without being spotted by the people who had the building surrounded.
At around 15:10 Billy escapes his room and starts walking through the main hall of the hospital by holding Dr. Dumont, his therapist, under her arm. At one point she is even greeted by an acquaintance.
At no point does anyone in a hall full of people find it conspicuous that a man wearing a mask with a freakish skull painted on it and with a hoodie over his head is escorting a woman who looks tense. Not even a guard and three police officers who run past the two without stopping to consider that a man wearing a mask, let alone a menacing-looking one, is an abnormality.
At no point does anyone in a hall full of people find it conspicuous that a man wearing a mask with a freakish skull painted on it and with a hoodie over his head is escorting a woman who looks tense. Not even a guard and three police officers who run past the two without stopping to consider that a man wearing a mask, let alone a menacing-looking one, is an abnormality.