When Boone and Briggs are treating the woman with liver failure, Boone mentions giving her naloxone. Naloxone, also known as Narcan, is only used to treat opiate overdoses or unconsciousness with unknown origin. Since the patient was awake with no signs of drug use, naloxone would not be used.
While Rabbit's actions are heavily criticized, his actions are consistent with what has been done in actual shooting situations. In real life the armored SWAT truck would have been used since multiple lives were at stake.
In the sniper shots, the gunshot is heard as the bullets strike. Due to the distance of the sniper, the bullets would strike and then the gunshot would be heard as bullets travel faster than the speed of sound.