Seeing traffic jams in Google Maps can really help you plan your route home from work. But a video posted this weekend seems to show that a traffic jam could be spoofed into Google Maps with nothing more than a bunch of phones piled into a little red wagon.

In the video, posted by Simon Weckert, a Berlin-based artist who focuses on examining the value and impact of technology, a man walks down some city streets pulling a wagon with 99 smartphones that all have Google Maps’ navigation turned on. As the man pulls the wagon, the streets get progressively redder on Google Maps. Those red streets would typically indicate a bad traffic jam — but the video shows that the streets were nearly empty.

Usually, Google determines where traffic jams are by pulling anonymized location data from phones running the Maps app. If there are a lot of phones on a road and they are moving slowly, Maps will show a traffic jam on that road. Lots of devices running Maps in the same spot is considered “proof” of a traffic jam, reported 9to5Google, after speaking with a Google representative.

Google jokingly told The Verge that it hasn’t “quite cracked” how to correctly track traffic data that comes from toy wagons, but that it can already distinguish between Google Maps data coming from cars and motorcycles in several countries.

It makes you wonder if Maps could be tricked in other ways, though. If a single person can fool Maps with a bunch of phones in a wagon, could others trick Google into creating actual traffic jams by using fake ones to re-route traffic?

Hopefully that doesn’t happen, but maybe Google will someday find a way to not show spoofed traffic jams like the ones set up in Weckert’s video.