At the start of their tour of the island in the tram cars, the cars are dry. As the tour continues, some scenes show the cars with wet windows, as if after a rain, then other scenes show the cars dry again.
Maybe it just rained some spots throughout the tour. Little spots of rain can dry quickly. And there was a storm over head. We keep being cut away from the scenes in the cars to scenes in the compound. Anything could have happened. Use you imagination.