Abby treats a patient with back pain and he asks for Vicodin. Abby assesses that he is allergic to Tylenol and Ibuprofen. Vicodin contains acetaminophen (known elsewhere in the world as paracetamol) which is the same active ingredient in Tylenol. If the patient was allergic to Tylenol, he'd be allergic to Vicodin as well. However, Abby is not assessing him, she is sarcastically listing all the excuses drug-seeking patients use to get Vicodin. Drug seekers don't always use logic when attempting to score.
During Sandy's surgery, when her heart is being shocked, Dr. Anspaugh calls out "clear", yet Kerry is still touching Sandy. You cannot touch a person being shocked, otherwise you will get shocked yourself.
Weaver tells Corday she met her wife Sandy at the hospital, but they actually first met on the scene of a vehicle accident in episode 8.8 "Partly Cloudy, Chance of Rain."