A good old scvenger hunt around Moscow sounds like a great idea!
So I did some mapping out on google to get the answer on which is faster: bus or subway? I used Pushkin Square as a starting point. By bus, it would take around 54 minutes to get to the All-Russia Exhibition Centre. There are many bus stops along the way, with buses comming every 30 minutes. By subway, it takes 28 minutes. There is only one stop in between, which requires the racers to take another subway. The first trip takes 3 minutes, with a transfer taking only 2 minutes. The 2nd trip takes 10 minutes. Subways run every 2 minutes. The only real problem with taking the subway is that it doesn't drop you off right infront of the pitstop. it takes another 10 minutes to walk.