This is the flag of the Republica de Miranda, a fictional South American country on the Argentinian film El Juego de Arcibel. The flag design is a horizontal tricolor similar in design with the flag of Latvia with the colors being (from top to bottom) green, yellow and black as you can see here in a black & white photograph at 3:03 and a few seconds later on the police station with the coat of arms in the middle here.

You can see a better image of the coat of arms in this video at 8:56 here.
José Eduardo González Vargas, 16 September 2008