This Is Us star Mandy Moore breaks down Rebecca's beautiful, devastating train ride

This Is Us just took viewers — and Rebecca — on a ride to remember.

Tuesday's lavish and emotionally devastating installment, "The Train," transported viewers to the long-dreaded end of the line for Rebecca Pearson (Mandy Moore). The episode tugged every heartstring it could find, brimming with heartache, hope, wonder, nostalgia, and gratitude for the matriarch who sparkled for so long before Alzheimer's snuffed out her magic. The episode employed the metaphor of a train — an idea that tracks back to the season 6 premiere — to reflect her passing on to the next realm. With Randall's biological father, William (Ron Cephas Jones), serving as the kindly conductor, she passed from car to car and reunited with familiar faces, all while nagged by the feeling that she was "waiting for someone."

While Rebecca began the process of crossing over in her mind's eye, her family was gathered in sad reality at the family mecca, saying their final goodbyes, but also hinting at new beginnings. (See: Deja's stomach and revelation to Randall.) The last, frantic arrival was Kate (Chrissy Metz), who flew back from London as fast as she could and ran to her mother's beside so the Big Three could be there for her last breaths. And as Rebecca reached her final destination in the caboose (a word she couldn't quite remember in the season premiere), she spotted a younger version of Kate. It was time. After William helped her to reconsider the sadness of endings, she climbed into the bed and turned over to see a special person who had already journeyed to the afterlife many decades prior: husband Jack (Milo Ventimiglia). They exchanged two words: "Hey" and "Hey." They were enough. They were everything.

Let's order too much Chinese food, pour ourselves a vesper, try to reduce cell inflammation in pancreatic tumors, draw really sad straws, and take a seat on the train next to Mandy Moore, who impressively assumed the reins of this family in the second half of the series and proved to be a mother like no other.

Ron Batzdorff/NBC Sterling K. Brown as Randall and Mandy Moore as Rebecca

ENTERTAINMENT WEEKLY: So, that wasn't emotional at all.

MANDY MOORE: Yeah. [Laughs.] It's why I threw up after reading it. I couldn't breathe. I remember seeing Chrissy the next day at work and she had not the same reaction — she didn't get sick — but it was one of those experiences where you're so overcome that your sinuses are completely blocked. You can't catch your breath, really. It wasn't even so much the saying goodbye and her turning and Jack is there at the end. All of that was just [blows exhausted raspberry] exceedingly beautiful, but I think it was being led by William and just all of these little Easter egg details. I don't know what all is going to be seen [on TV] — just the little bits and bobs from our life, the "Taboo" game was there, the growth chart from the kitchen in the Pearson house, there were just so many fun things for me to look at and be caught off guard by and really reacting to in the moment. What a beautiful, all-encompassing way to showcase someone's life at the very end.

What were your first thoughts when you learned that Rebecca would cross over in this train metaphor, reconnect with all these familiar faces, and see this wonderful jumble of her life as she passed through each car?

It's one of the most beautiful things I've ever read in my life. I wrote Dan [Fogelman] immediately after finishing it and was just like, "I'm so honored that I get to be a part of this and to tell this story, and to end this story in this manner just is wow." I never, ever could have imagined that this is what we would be doing at the end. It is the most beautiful metaphor, and my goodness, if this is what really happens to us at the end — it doesn't seem all that bad, you know? [Laughs.]

We should all be so lucky. What was the biggest challenge for you in calibrating your performance in this episode?

Because we got to live in a world where Rebecca was at her most cognizant, I feel like she was at a chapter of her life where she maybe felt like she was firing on all cylinders. It was nice to live in that world again, because for the last season and a half, we weren't really in this world anymore. This was the period of eight- to 12-year-olds and those kids grew up. So we've been living with the little littles, a bit of the teenagers, so I haven't existed in this space before. I think it was like where the marriage was the strongest.

It was a lot of fun to play back in this era, and to get to work with everybody in a way. It was funny to see my castmates as a younger woman — seeing Susan on the train and it's like, "Yeah, I'm not Rebecca present day when I'm with you, which is normally the case." And working with Gerald [MacRaney, as Dr. K] again and getting to work with Ron again — and not in present-day [old age] makeup and all of that, it was such a treat.

What was your favorite ahhh! moment before that final scene with Jack? Was it William as the conductor? Or Dr. K as the bartender? Or Miguel [Jon Huertas] with the glass of wine?

Everything. I guess initially it was William because that happens first, but Dr. K with the Terrible Towel being the bartender and making me my vesper —  Gerald is just such a special, special soul and actor. And the fact that we've worked together a few times now, but can just lock back into each other's rhythm in a special way. It's like, "Wow, we started this together." My first day on the pilot was working with him and to footnote it together again, to bring him back in at the end was just beyond my wildest imagination.

And it was so beautiful, the gift of [Dr. K] saying, "We had this moment, I thought I was going to lose you, and I think you knew it too." It was giving her that gift of: "You weren't crazy. I know you felt that." And then to tell her that she did an amazing job and she was an amazing mother — it was everything you could have hoped for.

Though short, the reunion with Jack is powerful. Would you call that a lovely ending or is there more of that scene — and of them — to come?

I would tell people to stay tuned. I mean, if that's all we get, I think that's plenty. Just the idea that at the very end of the day when she finally lets go, he's waiting for her. Ohhh! There's nothing more poetic than that. And I feel like if that's where it ends, that would be plenty.... In the finale, we'll definitely get to see a lot more of Jack and Rebecca at a time that we haven't really lived in very much as of late. So that will be a treat for people as well.

It was haunting to see that Jack scene in the hospital on Super Bowl Sunday from a different perspective.

I know!

Did you talk to Milo about what that was like for him?

Just the simple fact that it's like, "Whoa, I can't believe we're back here again. This is so weird." [Laughs.] I don't think any of us would've predicted in the final moments of the show that we would ever touch that time period again. And it was sort of haunting, because they shot me walking through in the background, with his belongings, walking to the car. And then they shot me getting the candy bar again and turning around right before I was supposed to talk to the doctor. It was spooky to be back there.

How much did you and Dan talk about the need to balance the sadness with the sweet in this final run of episodes? Did that make it easier to wade through, knowing that for every scene that might stomp on your heart, there was a sweeter, nostalgic moment to act as salve?

There was a balance in the script, even though it was heartbreaking. The train is really beautiful and it's almost psychedelic — or at least my reading of it was. I'm not sure how it looks on screen and how it feels on screen. So I think that the family sitting at the bedside and the reality of really watching somebody slowly slip away, juxtaposed with this beautiful, magical world that's inside her brain that we get the honor of walking through with them, I think helps.

Rebecca's not sad on the train. There are moments of insistence of like, "I'm not ready to reach the end yet because I am waiting for someone," and she knows that William knows that. So there's a hesitance there and maybe just a tiny bit of, obviously, the fear of the unknown. But I also think there is an acceptance and there is an embrace of this beautiful world of being surprised at seeing all of these people. I don't think she expected to see Beth and three different versions of Kevin and three different versions of Randall and Toby with little baby Jack. Just all of these vignettes of her life from very, very different time periods too. I think she's really caught up in the moment and the gift of being able to witness all of this. There's a levity, there is sort of a buoyancy of that, that I don't think exists in the reality of what the family is living through.

You've mentioned what this episode did to your stomach. Which was the moment that particularly wrecked you?

That's hard! The Dr. K stuff really got me, because it's not like he was an enduring presence in their life. She saw him during this very monumental moment of giving birth and losing a child. And then he came to Jack's funeral. She saw him when they were babies once. It wasn't this constant throughline. Or at least, like, there wasn't the physical presence in one another's life. I think she held him in such high regard and high esteem and had him on this pedestal. So the fact that they could have this very candid conversation about what happened during [the birth]— I imagine this event that Rebecca carried around with her, for the entirety of her adult life. But him giving her permission to take a rest, like you've earned the rest — oof, that really, really got me. That idea of you're so strong… [she trails off] sorry, I get emotional thinking about it… but for someone to tell her, "You lived a great life and you were an incredible mother and you had all of this tragedy befall you, and you still made such a beautiful thing of all of it. And now you're allowed to rest. I think just getting that [she starts to cry] permission from someone that she didn't even know very well, but loved so much and held in such high regard really just went such a long way. And that, oof, that got me. Still gets me, obviously. [Laughs.]

Ron Batzdorff/NBC Mandy Moore on 'This Is Us'

This dementia storyline was very ambitious, and you were already the only cast member working in all the different eras. What did you think about this challenge when Dan pitched it to you years ago? How daunting was the prospect of portraying this decline over time?

I was really nervous, just because this is the reality for millions and millions of people around the globe. And I wanted to make sure that we handled it respectfully and with dignity. I knew we would, but it's one thing to portray a 70-some-odd year-old grandmother and mother of adult children. It's another thing to be in the throes of that degree of cognitive decline. It's not just seeing her at the beginning of this journey; it's following her through until the very end. I wanted to make sure that we got it right. And I've been so blown away by this idea of representation for families out there who have lived through this, who are living through this with a loved one, who are the primary caregiver or just on the sidelines witnessing this, and for people to feel seen in a way that I don't think they ever really have in this context to this degree, considering that the show reaches as many people as it does.

I was just daunted by the prospect of making sure that we captured it properly and that it was accurate. Because there's so much stigma around cognitive decline and around our brain health. I just wanted to make sure that we were having an appropriate conversation about it and starting a real dialogue and helping to de-stigmatize it. What Dan and the writers have done was so careful and so exact — in the same way that they've handled tons and tons of other challenging and difficult situations and conversations. I think they really did such a great job. And I hope people who are living through this right now with a loved one or feel in community watching the show and feel a little less alone. And yeah… Whew. It's a lot.

I want to ask you a lighter question. What's one thing that surprised you about having to lie there for so long on the deathbed?

[Laughs.] Oddly, I had to go to a place mentally that I wasn't expecting. I was like, "Oh, I'm tired. I've been through all of this makeup. I'm just going to get to rest and take a nap all day." But then when people are coming in, pouring their heart out to you — when [Beth, played by Susan Kelechi Watson] came in and she was like, "I've been faking it. I've just been trying to do my best impression of you" — the first takes, thank God it was on her, because I'm barely supposed to be there and I have tears rolling down my face. I'm like, "This is not okay." I was like, "Okay, where can I put myself? And I was like, "I'm floating in the ocean, off the coast of Hawaii. It's a beautiful warm day. I've got a tropical drink." I was trying to put myself in some other world altogether. I thought I would be able to tune in and be in the moment and be present and just go, "Wow. My friends are so good at this. This is so beautiful." And the first take, I was like, "Oh no, no, no, no, I can't do this."

What can you tease about the series finale next week?

I think the simplicity of what's in store for people in parts of this episode is what the whole series is really about. People waiting for things to be tied up perfectly in a bow with every single character and every single story need to abandon that idea because that's not the reality of life anyway. You finish telling one person's story and it's like, "Yeah, but they have children or they will continue having a life. And their children will have children will have children. This story could just go on forever and ever and ever." But having said that, the simplicity and the beauty of the quiet, simple seemingly mundane moments of this family's life are going to feel like a warm hug for people.

If you threw up after reading "The Train," what did you do after reading next week's finale?

I cried just because it was the end. But it was not nearly as upsetting to me. I was like, "Ah, what a beautiful way to wrap this up." I just remember closing [the script], going, "You stuck the landing, Dan. You really did. No one's going to be disappointed." This is a really beautiful way to end this story.

This interview has been edited and condensed for length and clarity.

Say goodbye to the Pearsons with EW's special This Is Us edition, available to purchase online or wherever magazines are sold.

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