This is addressed in the final scene. It would seem that the crew of the Enterprise has been down to the surface of the planet to do a cleanup, including speaking to the locals to see what they think took place.
Although quite a few people, 14 by my count, saw some part of the gunplay, evidently their recollections are jumbled and don't belie any understanding of what they actually saw (e.g a light-pistol fight between aliens).
Archer: Captain's Starlog, July 21st 2151. We've removed the mining equipment from under the shop. As far as we can tell none of the Akaali knows what really happened... with one exception.
Riann tells Archer that it's vanishingly unlikely that anyone would believe her if she told them the truth (given their level of technology, it's likely that they think they were looking at fireworks or some kind of flammable liquid) and the episode draws to a close.