What is an accidental event that involves nuclear weapons that does not create a risk of nuclear war called?

So Broken Arrow the movie concept is taken here

Player #55741825, life altering (?) weapon is also a gun. I presume there are millions of them missing or unregistered.

The movie Broken Arrow with John Travolta and Christian Slater.

Shouldn’t be an issue in the first place,hate the fact that we have life altering weapons going missing