From the foreground to the background, Paul Feig and the rest of the crew used digital effects to fully realize a genuine ghost attack in a huge, crowded theater.
Over the course of two minutes we see several unique scenes from the film, and a breakdown of how certain shots came to life.
Some sequences look almost entirely digital — such as the rats flooding out of the subway station — while others actually combined actors and practical effects with advanced CGI work.
Without question the most impressive sequence in the entire clip comes towards the end when we see how the cast and crew of Ghostbusters crafted the heavy metal concert scene.