Well-written episode. Just a few problems I had with it, and those refer to the medical side of things.
1) When you come across somebody in cardiac arrest, the first thing you do is start CPR, not rush them into the ER. When life is at stake, seconds count.
2) You can't shock asystole (absence of any electrical activity in the heart, which was what Elisa had). Asystole is incredibly difficult to bring someone back from, and I am quite surprised that she would already be in that rhythm, since it's not a typical initial rhythm after cardiac arrest, particularly since Elisa is young and (we presume) otherwise healthy.
3) When your patient converts back to a normal sinus rhythm, you first check for a pulse-you don't automatically assume they have one (it is possible for a person to be in a sinus rhythm without a pulse; this is an example of pulseless electrical activity, or PEA).
I guess I'm a bit biased because I'm a nurse, and I understand how things work with medicine in the real world, which is often very different from what's displayed on TV. Otherwise, I thought that this episode really gave a message to kids about the importance of being responsible and NOT playing with real guns. (Also, gives an important message to parents about ensuring that guns are kept locked up where children can't get hold of them.)