They yanked the plea deal before the timer expired. Curiouser and curiouser.
I could see a perfect storm of inflated egos, a kid our of her depth as an armorer and that a*****e being over the top. I've seen similar behavior in high end lawyer'a offices and in a former customer of mine. Sometimes you get someone who is just an ogre and everyone around them is in a perpetual state of 'flinch' waiting for the next explosion and not giving their work the correct amount of attention because of it. That's how mistakes get made.
That said, WTF was she thinking bringing in live ammo? What possible purpose could that serve? I think she and maybe some others were plinking with the goddamned guns for the movie - that's what it sounds like. Stupid and even stupider to mix it in with blanks. They are so physically dissimilar I don't understand how a blank could be confused for a live round unless someone simply didn't look. That's why she got locked up.