This Last Of Us Season 2 Episode 4 Scene Took A Full Week To Film

Get off the subway right away if you haven't watched "The Last of Us" season 2, episode 4, "Day One." Spoilers lie ahead!

"The Last of Us" is, ostensibly, about a massive cordyceps virus that sweeps across the world and infects people, turning them into strong and bloodthirsty zombies. Still, the bloodshed we see on screen often has nothing to do with infected hordes; in this post-apocalyptic world, humans turn against each other constantly. The second episode of the show's second season, "Through The Valley," featured a massive attack — this one by an infected horde, to be fair — on the settlement of Jackson paired alongside the brutal and very personal murder of Joel Miller (Pedro Pascal) at the hands of Abby (Kaitlyn Dever), showing us the ways violence manifests in every part of this world. Then, in season 2's fourth episode, "Day One," Joel's surrogate daughter Ellie (Bella Ramsey) and her best friend Dina (Isabela Merced) travel from Wyoming to Seattle to find Abby, resulting in another huge action set-piece that brings all of these things together, somehow.

Here's how it all goes down. As they try to track down the Washington Liberation Front, or WLF, Ellie and Dina discover bodies of WLF soldiers, or "Wolves," strung up by Seraphites, a religious cult that stands in opposition to the military group. Before long, they're surrounded by WLF soldiers who end up summoning a whole lot of infected beings, with Dina and Ellie barely escaping through Seattle's subway system. As Merced explained in an interview with Variety, filming this entire sequence was, to put it lightly, intense.

"It was massive," Merced replied, responding to a question from Kate Aurthur about filming the subway scenes. "Oh my God. And it was definitely really challenging. I think we spent a week in there, I don't even know. It felt like a blur. And whenever we could, we would just try to escape outside and get some sun. It was really, really dark."

Now that we know that Isabela Merced and Bella Ramsey were stuck on this subway set for a significant amount of time, we can talk about Merced's next revelation, which is that the set decoration was a little too real for her taste. "And I just remember fun facts about that, I guess, would be that [set decoration] is supposed to have some sort of soil and dirt as cooperated, but a lot of times they use the fertilizer, which has manure in it," Merced continued before presenting the literal opposite of a fun fact. "But they didn't have enough time to prepare, I guess, so they brought in the manure and it hadn't had time to air out. So the majority of that experience, it smelled like sh*t. It was really disgusting. Also, Dina's doing a lot of cardio, Ellie's doing a lot of cardio running around. There are tons of infected, and it was actually just a crazy experience. So much happening."

Not only that, but Merced (a veteran of a particularly gruesome sequence in "Alien: Romulus") also found the scene with the WLF bodies difficult to shoot — due to the in-universe fact that Seraphites are really violent with their victims. "That was actually fake bodies, but they looked really realistic and they were hung up on that wall," Merced told Kate Aurthur. "And it was absolutely terrifying and disgusting, and it really ruined my day to be there. Uncanny valley is a term for a reason: The brain can only take so much false information that's appears to be real. "

"Yeah, it was disturbing and yeah, the vibes were hostile for sure," Merced continued, adding that thanks to her previous work, she was at least a little prepared. "It reminded me a lot of my experience with 'Alien: Romulus,' where it was just one level of fear, then the next level, and then increasingly just building that just to eventually reach the full-fledged adrenaline rush that comes with survival. I'm glad I had that experience, because it definitely trained me for this."

Not only does it sound like filming the subway sequence for "Day One," this episode of "The Last of Us," was smelly and gross, but Isabela Merced also revealed that the subway cars that she and Bella Ramsey had to climb, scale, and traverse throughout the scene moved, making it quite difficult for her to travel throughout the scene. "Yeah, they were actually rocking," Merced recalled. "I think they might've been on one of those mechanical stands, but also at the same time, they literally had the groups of people pushing on them. I could actively feel myself bouncing from one end of the car to the other, and then also having to shoot the guns in the right place — it was a really crazy sequence. It took a long time to do."

Here's something really fascinating, though: Merced said that she and Ramsey ended up creating a "secret language" on the fly to make sure that both of them were okay during this arduous shoot:

"But because of that experience, Bella and I ended up creating a secret language — that was the sequence in which we created a secret sign language to just communicate with each other about what it is that we were comfortable with or uncomfortable with when it came to what they were asking of us. And then also if we needed to pee or if we needed to ..."

When Aurthur followed up and clarified that the comfort level had to do with the physical activity in the scene and whether or not the actors used stunt doubles, Merced confirmed that doubles were always at the ready but that Ramsey wanted to jump in headfirst. "They were always there, and most of the time HBO preferred that they did it," Merced said of the show's talented stunt performers. "But Bella is someone very excited about the action, and maybe it's because they're younger than me, and I've been doing this for so long, I'm like, "Ah, I don't get paid to do stuff, so I'm good! There's somebody who has that job for a reason."

Still, Merced said that she knew she and Ramsey would be okay. "I didn't really feel unsafe ever," she concluded. "They were really on it. It's the perks of being a part of such a big-budget production." That's good to know, especially since we'll probably see more huge action set-pieces as season 2 continues.

"The Last of Us" airs new episodes on Sundays at 9 P.M. EST on Max and HBO.