Chicago is a big city. Like, really, really big. The makers obviously looked at what they wanted Ferris to do and decided to leave geographic and timeline reality in the dust as Ferris and friends drove away in a red Ferrari GT California Spyder.
Case in point: Ferris begins his day on the far upper side of Chicago, in one of those fancy North Shore neighborhoods past Northwestern University. He convinces friend Cameron—who lives in a different fancy neighborhood—to borrow his dad’s Ferrari, pull the subterfuge with his girlfriend at the school and then drive into the city. The clock is already ticking!
But then! A longish discussion with the parking garage attendants. Sightseeing at the then-Sears Tower. Lunch (impersonating Sausage King Abe Froman). More sightseeing at the Chicago Mercantile Exchange. A Cubs game! (Games typically last 3 hours, by the way.) Then more sightseeing back downtown at the Art Institute, followed by an epic parade crash. By this time, it must be nearly midnight! But no, it’s back up to the northern suburbs (presumably during rush hour) followed by an emotional discussion about life and love with friends, a ridiculously long footrace home and… Ferris is back in his bed by the time the folks walk in. By our math, those shenanigans would’ve taken roughly, oh, two days! Or at least 26 hours.
This would not be the first time a movie took liberties with geography (see another Chicago example here). It is easy to think why a film would do this: they want to have characters move in places that are well known, they do not necessarily have to adhere to rules of space and time, and the point of this film is about teenagers having a crazy day in and around the big city.
At the same time, films (and TV shows that follow similar logics) present a distorted view of cities. I could see this working out in two ways in Ferris Bueller. First, they visit the most well-known sites of the city. These can be fun locations, full of people, recognizable around the world. Ferris and friends have fun there. But, this reinforces only certain parts of Chicago and the surrounding region, missing out on a lot of other interesting sites. Second, their visits are quick in and out trips. They drop in, see the most important parts, and leave. In other words, not only do they primarily visit tourist sites, they are the ultimate tourists: they consume and move on and then return to mundane daily life.
These issues are on top of the time and space concerns of the film. Perhaps most viewers do not care about any of these; Chicago looks like a fun place in a time when the city (and other big cities) faced major issues. But, if viewers see enough films and TV shows that do this, they take in a limited perspective of cities and urban life.