Far be it for me as an amateur to critique the work of experienced professionals... but since you asked here are my thoughts.
1. The fact the opening sequence showed only females as the victims bugged me. Maybe that's just me.
2. It did not seem realistic that an intruder would start by banging on the front door. Usually home invasion starts by ringing the doorbell and trying to get the residents to open the door via some pretext or another. I'm surprised the LEO "advisor" didn't mention it.
3. I don't know if the budget would have allowed it, but using a professional stuntman would add to the realism when someone takes a hit/fall. If nothing else a bulletproof vest with ballistic insert would have allowed the first intruder to take the chest jab with more realism.
4. I would not feel comfortable in the safe room being so close to a ground floor window--with my back to it no less. Saying the bed was intentionally positioned there makes it worse.
5. I don't like the idea of security through obscurity. Sure things like a GunVault don't offer
that much security but it's better than hoping no one finds the handgun. Even if you don't have kids there's always the chance friends will bring some by. Better to always keep guns in a locked container.
6. Biometric devices may be neato tech but (at least right know) it isn't reliable enough to trust your life with. If your finger is too dry, too wet or positioned wrong it won't work. I like and use GunVaults. I don't know if the current deluxe versions allow multiple codes but the pre-company buyout ones did. I programmed in three codes (eg. 1-2-1-2, 2-3-2-3 and 3-4-3-4) that would enable me to open the safe regardless of which button I hit first.
7. In some states, cell phone 911 calls go to Highway Patrol and can take several minutes before dispatch responds. Then there's added delay transferring you to local dispatch. An old cell phone may be the final backup but it's better to have the local PD's emergency number on speed dial on a land line or active cell instead.
8. When calling dispatch, give the most important information first. In this episode's scenario, that would be something like "Home invasion in progress at 123 Some St. Two intruders, male." Pause to allow dispatch to notify/send units. Be prepared to give whatever suspect descriptions you can, state how many residents are there, where you are and the fact you're armed. The last bit is very important.
9. While probably realistic, I didn't like the resident's finger on the trigger. If someone else comes through the door you could have a bad shoot.
10. Speaking of defensive position, the best place is in a corner on the same wall as the door. Even with training it's easy for a person entering a room to forget about hard corners and neglect to clear them properly. That gives you that much more time to identify a person entering the room and make the shoot/no-shoot decision.
11. I'm not sure about announcing you have a gun to the criminals. Why give away a tactical advantage? Likewise telling them you've called the police. It lets them know they don't have much time left and have to act quickly.
That's all I can think of off the top of my head regarding the episode. I might think of more stuff later. Overall it isn't bad for the first episode of a new series. It's too bad the first season is already in the can; any input given now has to wait until the second season.
In terms of treading new ground, there are three areas I think a show like this should cover that haven't really been done before.
The first is what should you do immediately after a shooting. What physical/emotional stress you can expect, how you should inform dispatch about a shooting and prepare for officers arriving on scene. What kind of a statement you should give, and what you shouldn't say to avoid digging yourself into a legal hole later on. People have a natural tendancy to want to explain their situation and it's unfortunate that good intention can land you in legal trouble later on.
The second is dealing the the criminal and almost certian civil tort that will follow even a justifiable shooting. Most people don't think about getting liability insurance to cover themselves, and many of those that do fail to realize their umbrella liability policy may not cover self-defense. It may be better to be tried by twelve than carried by six, but giving your life savings, house and future earnings to the criminal's family isn't much better.
The third is dealing with the emotional aftermath of shooting someone. The psychological scars may surface immediately or take years before they manifest. Either way knowing they can happen and how to deal with it when they do is important.
Well, that's my two cents for now.