Your app to find Emergency Rooms nearby shouldn't be used in emergencies? I'm not convinced a disclaimer like that it's going to cover you.
For example: You've arrived in a new city. Open the app, see locations for ERs. Drive to each and familiarize yourself with the surroundings.
That might not be what plays out in court, but the problem there is people aren't reasonable.
I guess advertising the locations of hospitals and what hours they are open could be less fraught than advertising emergency rooms, but I'm not a lawyer.