Zack was extremely excited about the ponies when he saw them, and said, "Ride horse! Ride horse!" And he loved sitting on the pony for a minute. But then he was done. So he didn't actually go on the pony ride.
Zack recognized the stairs down to the subway station for what they were before we said anything about it---he pointed to them and said, "On train." In the middle photo, he is clapping along with the accordion music played by performers in the car.