Visible crew/equipment: When the SWAT team fires the grenade into the apartment at the end, the guide wire along which it is traveling is very obvious. It's actually easier to see in normal speed. (01:29:25)
Visible crew/equipment: Near the end of the film Leon tells Mathilda to grab the axe. As she opens the glass door to get it you can see the camera and its operator filming reflected in it.
Answer: No specific reason is given; it's most likely intended to highlight that her family are bad people (they are drug dealers after all) and to show in contrast that Mathilda and her little brother are not, so we feel badly for them.
Purple_Girl