I also think that the firing position is a little off, as Rasmus suggested she should be a lot more drawn out over the ground by moving her right leg back at a less steep angle and then extending her left outwards in the direction of the gun fire. She seems very scrunched up to the weapon as well she most definitely needs to have her right elbow raised to be horizontally in line with her hand.
Now for my original thoughts, so not reiterating another deviants points, the Muzzle flash just doesn't look right. Impact is right but its a bit over the top. If i stare at it for a while i start to like it but on first glance it needs work. It does seem to detract from the focus of the still being Jolene herself. however, everything else looks great, the dusty effect and the translucent texts really add a great quality to the style of picture. Would love to see how it looks with a different muzzle flash.