It was stated that Flynn's car was destroyed by someone tossing a Molotov cocktail (a glass container of flammable liquid with a rag lit on fire) through the side window. The car had exploded, which would not happen with a Molotov cocktail. If a glass container had been thrown into the padded/carpeted interior, it likely would not have broken, and even if it did, it would not cause an explosion as was shown. It would only start a fire, which would have been visible from where Flynn and Vega were seated..