Director of Until Dawn movie teases "very bloody bathroom scene" as he opens up on the challenges of filming a time loop horror: "It was everywhere, you couldn't clean it up"

Until Dawn director David F. Sandberg has opened up on the biggest challenges of filming a time loop horror – and as you might have imagined, most of them involve blood and gore.

"There were a lot of technical challenges. Like, the amount of clothes... the same set of clothes," he tells GamesRadar+, ahead of video game adaptation's release on April 25. "For Clover's outfit, I think we had 90 [sets] because there's so many different stages, then we had to have backups and clothes just for stunts. It was actually hard just to find so many of each, you know, pair of pants or whatever, so a lot of it [was created by] the costume department."

Then there was the scheduling... According to Sandberg, principal photography had to be planned out meticulously so that the most violent scenes were captured towards the end of the shoot. "It gets weird," he laughs. "You know, the bathroom scene where it gets very bloody? That, we had to shoot last because we just completely destroyed the set. There was blood everywhere. Like, you couldn't clean that up."

"Even the props that were in [other rooms], like, I have the guest book... I kept that and it's just, like, covered in blood. Soaked in it. So yeah, we had to do that [whole sequence] last which was kind of a bummer, because it was the one I looked forward to the most, and I had to wait the longest for, but it also the thing that turned out the best, I think."

Loosely based on the 2015 game of the same name, Until Dawn follows a bunch of twentysomethings, who get stuck in a time loop in which they're the targets of a bunch of terrifying threats. If they all die, the night resets, bringing about new beasts and baddies, from witches and wendigos to masked serial killers, for them to face off against.

With that, the movie plays out like a love letter to all kinds of horror flicks, from slashers to the supernatural. During one go-around, Sandberg even veers into found-footage territory, à la Paranormal Activity – as the characters catch themselves up on the nights they can't remember so well via videos on one of their phones.

"It was a lot of fun, because they were so standalone from everything else. They didn't have to connect to any other scenes. It meant I could do some things that I've been wanting to do forever. The worm in the face has been an idea I've had for a long time. The red hallway with the tall guy with the mask, who is actually me... we shot that on sort of a miniature set to make me look that tall. That's something I've always wanted to do. Just build a smaller version of a set to make someone look huge. They were all a little bit improvised, like, 'Okay, it's the end of the day, you only have these three actors, what can you do with that?" That's why not everyone is in [those videos], because we had to send, like, Ella [Rubin] home so she could come back early the next morning."

Sandberg, who has a blink-and-you'll-miss-it cameo in the movie, goes on to reveal that the script originally featured a scene where Michael Cimino's character Max stabs one of the franchise's most iconic monsters. "We ran out of time, we couldn't do it and I was so bummed about it. But we still had the Wendigo puppet, so it was like, 'Well, let's throw it into the found-footage stuff.' The glitchiness in that scene? Yeah, that was something I created myself because I was, I was very particular about how I wanted the glitching. So it was like, 'I can't let VFX do this. They're never going to get it exactly the way I want it. So I'll just do it myself on my computer."

Until Dawn releases on April 25. For more, check out our list of the best horror movies, or our guide to the most exciting upcoming horror movies heading our way.