It's interesting when seeing these giant sequences in films and what it really took to make it all happen. One of my favorite scenes in Avengers: Age of Ultron was the scene in Seoul and this featurette really highlights some of the major keys into making it successful. For instance having Marvel shutting down major highways is huge. For something of that scale to happen it would require a lot of preplanning and preparation. The sequence where Black Widow is on the motorcycle chasing down the truck was shot at full speed with a car traveling right behind it getting all the shots, though it was a stunt driver wearing a special helmet that acted as Widow's hair, it's intense to see that entire sequence(minus the green screen of Scarlett Johansson) is 100% real. In an age of CGI, it's exciting to see some massive sequences actually be practical. The stunt man for Captain America was actually on the truck going at a fast speed as well which really intrigues me with how much planning has to go into having an actor work with high winds blasting you on a moving truck with wires.

Check out the featurette. It's really quite something.