It's perhaps a minor point, but I don't believe Wolfram Alpha has the distances between each pair of cities in its store of facts: it has the locations of each

It's perhaps a minor point, but I don't believe Wolfram Alpha has the distances between each pair of cities in its store of facts: it has the locations of each city, and it knows how to calculate the distance between two locations on Earth, and it can decompose the query into such a calculation on two facts from its database.