Deliberate mistake: When the two lawyers were wheeled in by ambulance riding on the same gurney entered the ER the male had a bandage on his foot because they had been walking on hot coals. The hospital staff smelled smoke coming from the bandage on the male lawyers foot. It burst into flames and Abby used a Dry Chemical Fire Extinguisher. Something other than powder came out because the dry chemical powder would have made a large cloud of actor choking dust all over the set. The use of a C02 would have been a better choice. You would still get the fire fighting effect with out the mess.
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.