Second trip, the girls were 5 and 8, we were just relaxing in France on a bench. Dusk was falling. The kids wanted to buy something, and joked about fishing coins out of the fountain pool to pay for it. They sat on the edge of the fountain and were just swishing their hands in the calm water. Suddenly, the fountain lights come on for the night and it starts spraying water from the edge, right where they were. They were so startled and jumped and ran to us. A few people that noticed had a chuckle.
It's not a big or magical thing (well, sort of), and doesn't involve any characters or rides, but it's one that stands out.