When Jeff Probst began planning “Survivor” 50, he knew he had to go big. As always, that began with the cast — sifting through the 700+ castaways who have competed over the last 25 years to find the most memorable and iconic ones to return. Then, Probst quickly moved onto designing the season’s theme.

As revealed in the first trailer for this season, “In the Hands of the Fans” will include twists featuring Billie Eilish and Jimmy Fallon, and cameos from Jimmy “MrBeast” Donaldson and Zac Brown.

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But don’t fret, “Survivor” loyalists: Probst isn’t losing the plot.

“Once we committed to turning the game design over to the fans, the next question became: ‘How far can we go with this idea!?’” the host and showrunner tells Variety. “We knew some of ‘Survivor’s’ biggest fans happen to be celebrities, so we thought sprinkling a few of them in with their own unique twists felt like a fun way to make the game even more unpredictable! It definitely caught the players off guard in some really exciting ways, and added another layer to this celebratory season.”

This is the largest cast to ever play, and the castaways will, as always, be the real stars of the season — even when there are game-changing twists with celebrities attached. Variety was on set in Fiji for two of the collaborations, and can confirm that “Survivor” still feels like “Survivor,” even when A-list names are attached.

“I think it’s a legitimate concern when you start adding layers like celebrities, that they can overshadow the game and take it off course. Our job was to make sure that we stayed true to what we’re doing on ‘Survivor,’ which is exploring this continuous social experiment. And now we’re adding another layer,” Probst says. “And when you bring in a celebrity like Zac Brown or MrBeast or Jimmy Fallon, you now add idolatry, and you add different perceptions and reputations. Suddenly, people can get off track a little bit, or they lean in, and they want something to do with Jimmy Fallon. A lot of the players said, ‘I’ve always dreamed of being in a MrBeast video.’ So the twist is designed to see if you can stay on course with the thought process you should — or how is it going to shift your thought process, and will it do you in?”

He also adds that he didn’t go out to celebrities and ask who wanted to be involved — it was through his own friendships and relationships that each collaboration came about. And it was the celebrity’s idea.

“With Jimmy Fallon, it was on his show. Jimmy texts me ideas all the time about ‘Survivor,’ and we put some of them in the show, and we’ve always talked about this idea,” Probst says. That idea, for now, won’t be shared — but it is an exciting one, which is hinted at during the trailer, and didn’t go at all how Probst thought it would. “I think people will see, when they see these play out, I think they’ll understand these are legit ‘Survivor’ fans who wanted to be a part of 50.”

The biggest collab of the season, however, will be the one with MrBeast; Probst appears on Season 2 of “Beast Games” and Donaldson shows up for something on Season 50 of “Survivor.” The cameos were filmed days apart from each other in June in Fiji.

The crossover conversation began when Lori DelliColli, VP of communications at CBS, was eating breakfast, and her kids showed her a MrBeast video. One of his team members, Karl Jacobs, was wearing a “Survivor” buff and talking about the show. She flagged to the marketing team, who invited Jacobs, along with “Beast Games” co-creator Sean Klitzner, to participate in the influencer experience filmed ahead of Season 49.

No one knew at the time just how big of fans they were of the franchise. Executive producer Matt Van Wagenen recalls Klitzner applying and getting close to being cast on an earlier season. In 2020, Jacobs DM’d Van Wagenen on Twitter (as it was then), raving about the show. Van Wagenen mailed him a crew T-shirt and when Jacobs posted it on social media, the producer started hearing from friends and family. He had no idea how big Jacobs’ following was. Once they re-met in Fiji, “it felt like this was a conversation we never finished,” Van Wagenen says.

During the influencer experience, Klitzner pitched Probst on some sort of collaboration — and “the camaraderie was instant; my respect for them was instant,” says Probst. “And then it was Lori’s idea to say, ‘That felt like some synergy there.’ We’ve never said, ‘Let’s collaborate with another show.’ Ever. We are our own tiny little world trying to just stay out of the way, and do our show.”

A main part of the crossover, though, was logistics; the calendar for “Survivor” Season 50 and “Beast Games” Season 2 were already set. But the Prime Video reality competition series was willing to bend: They all wanted to make it work.

“I said, ‘Jeff, if you really want to do this, ‘I’ll push my entire shoot. I’ll fit your dates no matter what,’” says Klitzner. “We had a kick-off meeting where they pitched us what we should do for our show. They said, ‘We don’t want to overstep.’ We said, ‘We want you to overstep in every sense of the word.’ They said they could shoot it with their crew and could build challenges. They came in, designed everything from soup to nuts. And of course, then our team came in, and we put ‘Beast’ into it… There was not one moment that Jeff went, ‘I don’t know if we can do this.’”

Though “Beast Games” and “Survivor” are both reality competition shows, they have very little in common.

“They have a chaotic approach. They have cameras everywhere; they break the fourth wall all the time. They talk to players whenever they want. It’s a completely different form of storytelling, and it works,” Probst says. And Donaldson is a very different type of host from Probst. “He’s not focused on a longer-term story. He seems more focused on an in-the-moment reaction, and they bounce from one reaction to another, to another. It’s similar to his online environment, which is this constant hit of another moment, another event, one after another. “On ‘Survivor,’ we’re looking at the long game. We want to introduce you to somebody, let you know who they are, where they’re from, what their vulnerabilities are, and then we add things to the game to exacerbate that uncertainty and force adaptability.”

And Donaldson’s style was “exhilarating” for Probst to see, allowing him a look into such a different production than he’s used to. “Who knows what influence I will take from that?” Probst says. “I’m sure in some ways, I will take things from my time with Jimmy and go, ‘I could use some elements of that in ‘Survivor.’”

In a way, it was “like I was in a video game and just trying to keep up,” Probst says of being part of the “Beast Games” episode. “He just goes wherever he wants. He, like me, is the producer of his show. He can decide to do whatever he wants, and he does. He doesn’t hesitate to say, ‘I think I’ll just bribe you with money right now.’ It was fascinating to be inside their world and watch them.”

Of course, having Probst by his side was a huge learning experience for Donaldson — both as a host and as a producer. After the first part of the collab is filmed, Donaldson says: “I’m a little more monotone. Jeff projects his voice, and has a swag with certain things — like Island swag! I would love to have more presence with my voice like he does.”

From a producer’s standpoint, Donaldson realized while in Fiji that maybe “Beast Games” has “over-indexed on changing things. He’s essentially done similar vibes for 25 years, and it’s still cool. People like familiarity, and I usually try to mix things up, but that makes the production way harder,” says Donaldson. “It’ss helped me realize that not everything has to be fresh, because sometimes fans just like things, and if they like it, do it over and over again.”

But after figuring out how “Survivor” would be incorporated into “Beast Games,” it came time for Probst to figure out how to mix MrBeast into his show.

“The key point for me was, our show is not changing. Jimmy will come in, and we’ll bring the aspects of ‘Beast Games’ that we want to explore on our show,” says Probst. “If you look at the two shows, ‘Beast Games’ asks one question: What will people do for money? ‘Survivor’ asks a different question: Who are you when you’re stripped of everything?”

What Donaldson’s role is in “Survivor” 50 needs to stay secret for now, other than what’s shown in the trailer: He shows up with his briefcase. Let’s just say, what’s inside has major potential to change the game.

“When you take people who are being stripped of everything,” Probst says, “and then you bring in maybe the most well-known person for unpredictable moments, it took the uncertainty to another level.”

“Survivor” premieres on CBS Feb. 25 at 8 p.m. ET.

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