Other mistake: She has a Glock 26/27/33 or 39. They are all different calibers but the same exact frame. The Glock is striker fired, so for it to be functional and loaded with a bullet in the chamber the trigger has to be in the fully forward position, however in this scene the trigger is fully depressed. For the gun to be loaded and for the trigger to have movement, the slide would need to be cocked so the striker is cocked and that would move the trigger forward so it could be squeezed and fired. (00:45:00)
Other mistake: At the very beginning when Riley shots the dude in the head, the blood comes out but the bullet does not break the glass.