Watching Squid Game is a nail-biting, heart-pounding experience, but making it was arguably just as terrifying — particularly filming the fifth challenge, which sees the players attempt to traverse a tall bridge of glass stepping stones without breaking the panels and falling to their deaths. Just another totally normal day on the set of Squid Game!

“I think the reason why that scene was realistic was because the set itself was a little frightening for the actors,” creator Hwang Dong-hyuk explains in a behind-the-scenes featurette.  “The fear portrayed on-screen wasn’t fake.”

That’s certainly true of Jung Ho-yeon, who recalls, “It was actually pretty scary because the glass bridge was built about one meter above ground, and we actually had to jump between the tempered glass panels. We did have safety guards on site, and everything was set up securely, but I was scared to jump between the glass panels.”

The shots of the players falling were even scarier to film as they were even higher up, about 6 meters from the ground. Don’t worry, all the actors were attached to safety harnesses — but since filming each challenge took anywhere from a week to ten days, according to star Lee Jung-jae, that's a lot of terrifying days at work.