Character mistake: When Dr. Keaton rushes back into the OR to take over from Peter, she moves forward, pushing the door open with her hands. No surgeon would EVER enter an OR this way-it would contaminate her hands. The proper way is to back into the room, keeping one's hands in the air and free.
Character mistake: Carter tells the mother of the smallpox infected children that no one has seen smallpox for 50 years. The episode aired in 2002, WHO didn't start its global eradication of smallpox until late 1950's and the last case was reported in 1978, which is only about 20 years.
Character mistake: In the season 8 episode 'Never Say Never,' In the opening scene before the credits, Dr. Susan Lewis returns to the ER to meet with Mark Greene for lunch. She is standing at the admit. desk and asks Frank, then Luca where she can find Dr. Green. The shot then pans out to a view of her back, exposing the curtain areas. In that shot, Dr. Green walks right past her, no more than 10 feet away. Due to their angles, there is no possible way neither of them would have not seen each other at that moment, yet he walks past, and she continues her hunt for him.