1) I agree wholeheartedly that the entire scene is artistic vision: IE, this is the way Aoyama drew it so, in his opinion, it would have the best impact. Not realism.
2) That aside: handguns are notoriously imprecise. You aim handguns (using a nice stance like a Weaver) at center mass, and not at things even partially obscured by other things you don't want to hit. You are never too close to miss.
Also Ran had no way of knowing there was a sniper out there- she couldn't even clearly hear the conversations, she just heard voices and shots. I say this, because if she'd heard clearly, she'd know more.
Finally, the sniper did have a shot. Remember? Vermouth stopped him because she did not want to risk it. It's pretty clear in the page Chekhov posted- notice the off-hand shooting at Calvados? Pretty obvious 'Do not take the shot.'
And I'm going to have to agree on the inside trunk release. Not because I've ridden in the trunk, but because in my first POS, oh, so many years ago, the trunk catch was broken. What I did was I usually left the back seats down, anyway- so I could put my portfolio in- and I'd lean in and hit the release from the inside to open the trunk. True story. Oh, I miss that '84 200SX. (No, no, I don't.)
And besides a trunk release- I'd always assumed, because of the force with which the image was portrayed (haven't gotten there in the anime yet) that Ran had kicked the trunk open. Latch Vs. Ran = broken latch. Then she jumped dramatically onto the roof. Then she took a running jump at Ai. Because she has the common sense and self preservation instincts of a lemming. But I love her anyhow.

