Continuity mistake: As Mark futilely pounds on Jodi O'Brien's chest, Carol can be seen in the background, removing her protective glasses with one hand. However, after the Time of Death has been called and they're showing the reactions of everyone present in the room (Susan, Carol, Carter, Lydia, Chen), Carol is seen taking the glasses off again, this time with both hands.
Continuity mistake: Peter goes into the operating room, demanding to help with his mother's surgery. When he goes in, his cap is pulled down over his hair, but when he is talking to the surgeon in charge, about an inch of his hair shows for a couple of shots. The surgeon orders him out, and he leaves, and his hair is completely covered again. At no time did he adjust the cap.
Other mistake: When Jodi O'Brien is having seizures during the birth, Dr. Greene decides to take the baby out prematurely. Complications result and the woman dies, they show a shot of a clock in the background and it says 7:00, but when they say the Time of Death they say 6:02.
Answer: A man named Paul Sobriki comes into the ER in the season 6 episode 13 " All in the Family." He is complaining of headaches, Carter and Lucy decide to rule out meningitis and do a lumber puncture. Paul struggles during the procedure and believes that both doctors are stabbing him. Lucy, who is interested in Psych thinks something is wrong with their patient mentally, but Carter is dismissive of her. She gets cross with his attitude and she calls the psych department anyway to have a look at him. Later on and near the closing 20 minutes or so of the episode, all the staff start playing loud music and get a cake which appears to be blue lol, together to party as it's Valentines Day, Carter returns from somewhere and asks where Lucy is. He goes to check one of the rooms for her and Paul Sobriki comes up behind him in the dark and stabs him twice in the lower back, he collapses and as he falls unconscious he sees Lucy on the ground also. In the next episode, Be Still My Heart (ep 14), Dr Weaver discovers them and all of the staff work to try and save them, whilst Carter survives. Lucy's wounds are fatal and suffers a pulmonary embolism as Corday and Romano try to save her. Carter is grief stricken and feels guilty about the way he treated her, he becomes addicted to painkillers and Benton, Greene all help him and book him into rehab.