Seems to be lots of misinformation on the Glock pistol. If indeed this was a Glock and the trigger was pulled it did exactly what it was designed to do ..... it fired. The glock actually has 3 safeties unlike most revolvers which don't have any (unless you consider a heavy trigger pull a safety).
The Glock Safeties
Glock Pistol
I would also add that if you are carrying a semiauto with an empty chamber you need to study the George Zimmerman case closely.