It is said that a grenade contained benzoyl benzoate, and that it is acetone. This is wrong. Benzoyl benzoate is the ester of benzoic acid and benzoyl alcohol. Acetone is the same as propanone, the simplest ketone. It lacks any aromatic units such as found in benzoyl benzoate. Also, ketones are distinguished by lack one oxygen atom from the defining bridge structure of esters.
When the police are firing upon Jason, Justin Bieber when they switch perspective, not only does the gun disappear, but the way his hands are positioned changes as well. In the angle from behind he has both hands raised, as if he were surrendering, and he is not holding a gun. When the angle changes back to the front, his arm is outstretched and he is pointing the now present gun at the cops.