It's Luke's X-wing which the previous shot cuts to (he's walking to it-away from the Falcon in the storm). They started to fade in that flash effect to transition to the Blu-ray art for the end of the tag and in the transition the first frame or so of the next shot are visible.
Of course we would have to go through this frame by frame. ;)
I'm surprised at the quality being presented, but then again I'm surprised that we're seeing these at all.