The problem with those "pictures" is that they're actually stills captured from a video camera. Even if it was a true HD camera, that's just 1920x1080 @ 72dpi, a far crappier resolution than it is even possible to buy in a still camera today. But, to my eyes, we're seeing a DENT in the roof, not a hole. The jagged edges are flaking paint. Whatever is rattling around in the headliner is part of the car that got broken off by the impact. Maybe a shard of plastic inside an A/C duct? Anyway, I predict that there will not be a bullet found.
Which doesn't mean it didn't happen. I've seen a lot of bullet holes, and bullet dents, and they do look like that crappy picture.