While Jamie and Eddie are talking in the hallway, the clock behind Jamie changes from 11:10 to 11:50 and back several times.
The young black girl who OD'ed on heroin was kept overnight for observation. Heroin is rapidly metabolized to morphine which has a half-life of 2-4 hours. after 12 hours of observation which is at least 3 half-lives, 1/8 or less of the heroin would be left in her system. That would hardly be enough to cause death. Also, hospital would not have discharged her with a lethal amount of heroin or morphine in her system.
In the scene where officer Reagan administers Naloxone, he is show injecting it into her arm. Unless a state certified paramedic, Naloxone is always administered as a spray in the nostrils by other first responders.
When Danny is trying to apprehend the groundskeeper, he pulls his gun. A gun cocking sound is heard, but he does not cock the gun.