"It's pretty incredible how they do it," Williams' fellow coach, Adam Levine, added. "It's so impressive. It's kind of down to a science."
Music lovers are used to seeing concerts with many different elements, but with several mini concerts taking place within a single two-hour episode, The Voice pushes its crew further than any regular stage show.
"With television it's a little bit different," said performance producer Jeri Slaughter. "The turnaround time is crazy. It's fun at the same time, because it kind of keeps you on your toes."
A team of 70 stagehands have about three and a half minutes to switch out one huge group of set pieces for another. Those elaborate set pieces include smoke machines, fire-spitting pipes, and flashing light towers.
Watch the video to see the army of production workers do their magic in between commercial breaks, while the contestants prepare for the opportunity of their lives. The Voice airs Monday and Tuesday nights at 8 p.m. ET/PT on NBC.