IT: Welcome to Derry Producer Explains the Finale's Movie Tie-Ins and Mid-Credits Scene

Warning: Major spoilers for the Season 1 finale of IT: Welcome to Derry follow. 

The first season of IT: Welcome to Derry wrapped with a finale that introduced a notable new element to the ancient creature known as IT (and his favorite form, Pennywise the Clown) that will certainly impact potential future seasons. And on top of that, there was an exciting mid-credits scene that more directly hands off this 1962-set prequel series to the events of the first IT feature film, thanks to the surprise appearance of one of the stars of that movie. 

In the finale, when Pennywise (Bill Skarsgård) confronts Marge (Matilda Lawler), he reveals he perceives all of his existence at once rather than experience time linearly. That means he is aware of what his future holds, including that Marge will eventually have a son, Richie – named after her late friend — who will go on to play a major role in IT's demise (Richie was played as a child by Finn Wolfhard and as an adult by Bill Hader in the IT movies). As the clown puts it, "Tomorrow, yesterday… It's all the same for little Pennywise!" 

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This puts a very different spin on the proposed second and third seasons of the show, which are planned to take place in 1935 and 1908, during earlier IT "cycles," given the creature awakens every 27 years. Now we know that IT is not only aware of how he dies, he is actively trying to stop it from happening, Terminator style, by killing those whose bloodline would lead to it occurring. So while Season 2 and 3 would still be prequels, it seems they'd also effectively be sequel stories too, at least from Pennywise's perspective. 

Speaking to TV Guide about the finale, Welcome to Derry executive producer Barbara Muschietti noted this time-bending concept was innately enticing to her brother, fellow EP and Welcome to Derry director, Andy Muschietti, explaining, "It's unavoidable for Andy to tackle a story without that component. He is obsessed with time. Our dad is obsessed with time and the plasticity of it. Is it real? Are we experiencing time the way time really is? It's something that has always, always fascinated us."

She noted the idea of incorporating this aspect came very early on in the development of Welcome to Derry, both because of their established interest in the idea and because of a conversation they had with Lost co-creator Damon Lindelof where he mentioned often not liking prequels because he knows how the story ends. That conversation inspired her and her brother to decide, "We had to reverse that. And that is very much the intention. I can't tell you more of that because I don't want to give spoilers for what you'll see and what the plan is if there are more seasons. But yeah, we needed to subvert that." 

The reaction to Welcome to Derry has been highly positive and the preliminary numbers for the show have been strong, though so far, no renewal announcement has been made. Regarding the wait to see if Season 2 and 3 are greenlit, Muschietti said "Listen, we want it. I think HBO wants it. So I think all the parts want it. The thing is, there's a high bar and it's not a cheap show. So there's math to be made and hoops to jump through, that kind of thing. But we definitely want to do it!"

The very end of the finale consists of two connected mid-credits scenes — or at least scenes that play after the show's title has appeared onscreen — involving Ingrid Kersh (Madeleine Stowe). In the first, we see Ingrid now locked up in Juniper Hill asylum, following her last encounter with Pennywise. In the second, we jump forward to October 1988 and see an elderly Ingrid still locked up, but now played by Joan Gregson, the same actress who portrayed Mrs. Kersh in the 2016-set events of IT: Chapter Two. That movie's Mrs. Kersh was in fact IT using Ingrid's form, in the same way IT so often looks like her father, Bob Gray, the real life Pennywise. But in this new 1988 scene, the real Mrs. Kersh hears a commotion from down the hall, which is revealed to be the suicide of another patient that has been discovered by this woman's husband and daughter… with the daughter turning out to be none other than one of IT's main characters, Beverly Marsh, and Sophia Lillis returning from the IT films to reprise her role as the child version of Beverly. 

As it turns out, this 1988 scene was only added to the show this past April, well after Welcome to Derry had wrapped production, while they were filming a few pickup shots for the series. Barbara Muschietti recalled that while they were flying to Toronto to film these pickups, Andy told her, "I just need a better tie to the films" when it came to the ending. Completely coincidentally, the Muschiettis' longtime camera operator Angelo Colavecchia had recently mentioned working with Joan Gregson again on a different project and that got the idea rolling to have the older Mrs. Kersh in one final scene that would also involve Beverly. 

Barbara Muschietti said the immediate concern about this idea was her pointing out to her brother, "I don't think we have any money [left in the budget]. We really don't have any money.' And immediately he's like, 'We'll find the money!' So we went through the visual effects budget, which is an insane thing to do, and we found a little money and we decided to shoot that scene."

Barbara Muschietti had huge praise for both Gregson and Lillis for their participation, saying of the late Gregson, who passed away in June just a few weeks after filming her scene, "That woman was a miracle. Just what a soul and we shot this when she was 91! She had such a great time in the shoot and she was so happy to be there." 

As for Lillis, Barbara Muschietti personally called her in New York, explaining to her, "'So Andy has this great idea, but we really don't have any money… It would be scale [pay], because it's also something that's hard to sell at this point.' And she's just the greatest. She said, 'I want to do it.'" 

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Lillis quickly flew to Toronto to film the scene and Muschietti noted, "We pulled the costume from the archive. She wore her same costume [from the movie], same shoes, the whole thing, and we shot it with her in long hair [in a wig], because this scene, of course, happens before the first movie." 

Lillis was 14 when she filmed the first IT and 23 when she filmed her Welcome to Derry cameo, but no special effects were used to de-age the actress, who still looks quite youthful. Said Muschietti, with a laugh, "She has not aged. It's amazing! But no, no de-aging. We didn't have money. If I had said the word 'de-aging,' they would have killed the whole thing. So I'm like, 'Well, she looks just like she did' and it's true!"

Regarding other elements of how the season wrapped up, the penultimate episode included the heartbreaking death of Rich (Arian S. Cartaya), one of the core group of kids we've followed all season. In the original IT story, all seven of the so-called Loser's Club survive their childhood encounters with IT (though obviously things don't go as well for a couple of them 27 years later), and Muschietti said that everyone agreed that shouldn't be the case on the series as well. So while they already pulled off quite a surprise with the shocking deaths of three kids who felt like they'd be ongoing characters in the show's first episode, someone else wasn't going to make it to the end. As she put it, "We needed to lose one of the kids. And we went through all of them [as possibilities]. We went through all of the characters and tried to decide the impact. And believe me, it was heart-wrenching to do it." 

Muschietti regretted some additional plans for Rich had to fall by the wayside, revealing "There was a much bigger backstory of Richie and his Cuban family. Sadly, we could not fit it in in the size of the show. But yeah, it's just a character we adore, as we adore Arian Cartaya who plays Richie. It was brutal."

Of course, Rich's death ended up not being the last time we saw him, as he returned as a spirit in the finale to assist his friends in trapping Pennywise within Derry again and then to comfort his parents at his own funeral — unseen by those other characters, but visible both to the audience and, ultimately, to Dick Hallorann (Chris Chalk) thanks to Dick's shining abilities. Speaking a few days before the episode would air about Rich's big moment during the kids' final showdown with Pennywise, Muschietti remarked, "That's the moment that I can't wait for people to see — when he comes running into the ice, that moment. I wish I could be in every home watching that, because I think people are going to cheer." 

While all the kids on Welcome to Derry had it rough, to say the least, Lilly (Clara Stack) went through a tremendous amount throughout all eight episodes, with Pennywise targeting her physically and psychologically numerous times. By the end of the finale, Lilly's friend Ronnie (Amanda Christine) has very understandably left Derry with her dad, Hank (Stephen Rider), and we have an idea of what's in store for the other kids, Marge and Will (Blake Cameron James), with both of them destined to eventually have children of their own who will be central to the story of IT. That leaves Lilly as a big question mark, since she's never mentioned in IT, and it's not clear if she is still in Derry when the next cycle occurs. 

Said Muschietti, "Poor Lilly… Lilly has it tough because she's so alone. I would hope that Marge and her support each other and at 18, leave town." Of course, Marge would have to eventually return to Derry, given she raises Richie there, but Muschietti said in her mind, Lilly stays away and that even Marge has a relatively happy life… at least by Derry standards.

IT: Welcome to Derry is streaming on HBO Max.