After building up to and finally showing the long-awaited prison break in Episode 5, Escape at Dannemora‘s sixth episode flashed back and showed viewers how David Sweat (Paul Dano) and Richard Matt (Benicio Del Toro) ended up in the prison, as well as how Tilly (Patricia Arquette) and Lyle Mitchell (Eric Lange) started their relationship. And, well, these are not good people. Maybe you were happy for Sweat and Matt when they finally regained their freedom, or maybe you were satisfied when Tilly did the right thing and didn’t poison her husband so she could help Sweat and Matt escape. But then you watched Episode 6 and felt revolted about ever rooting for these people. Sweat is a cold-blooded cop-killer, Matt is even more psychotic than you realized, Tilly is a faithless manipulator, and even sweet, simple Lyle has done some unsavory stuff.

Shot on grainy 16mm film that gives it an entirely different look than the rest of the show, Tilly and Lyle’s sequence takes place in 1993, when Joyce was married to her first husband, Kenny (Charlie Hofheimer). They both worked at a shoe factory along with Lyle, who was married to a woman named Norma. It showed Tilly, frustrated with her humdrum life, having an affair at work with Lyle, just like she would later do with Sweat and Matt. Her marriage with Kenny falls apart in screaming public fashion, and she persuades Lyle to leave his wife and help her get full custody of Kenny Jr. by goading Kenny into beating him up in the bathroom at work. Lyle is complicit in his own way.

Eric Lange, Escape at DannemoraPhoto: Christopher Saunders, Christopher Saunders/SHOWTIME

TV Guide talked to Critics Choice Award nominee Eric Lange about the stunning episode, and he shared some previously untold information about the creation of Episode 6, which he calls a “brain-breaker.”

According to Lange, Episode 6 was the last episode on the filming schedule, and the original plan was for he and Patricia Arquette to slowly over the course of the shoot lose some of the weight they’d put on for their roles so that by the time Episode 6 came around they’d be a little thinner for the scenes set 22 years earlier.

“And then [director] Ben [Stiller] came to me one day and said, ‘I’ve talked to Patricia about this, and she’s game, but what do you think about taking a month off, stopping production, and you lose all the weight you can, and then we come back and shoot for like a week in Upstate New York?'” Lange recalls. “And I was like, ‘That’s great, but my son is due.’ My son was due right around that time, and so I was a little nervous about that, but that’s what the plan was.”

So production shut down, and Lange went on an intense low-carb diet. “I lost a lot of weight pretty quickly because I had carried that 40 pounds around for about eight months at that point, and I was really ready to get back to my normal body,” he says. And then his wife had some complications with her pregnancy, and their son had to be born early. “I didn’t want to miss that, so production actually delayed another three weeks so that I could hang around and make sure I was there for the birth of my son, which was an amazing, generous thing for them to do,” he says. It also gave him time to lose some more weight. He weighed 212 pounds during production on the first five episodes and Episode 7, and by the time he returned to New York for Episode 6, he was back down to 175.

“And Patricia’s the same,” he says. “I think we both lost about 35 pounds. We both gained 40 for the show, and then lost about 35 just for Episode 6.”

Escape at Dannemora Review: Patricia Arquette Is Amazing in Showtime’s Thrilling Miniseries

A long break for actors to lose weight was one of many ways that production on Dannemora was unlike that of a typical TV show. Another luxury was an incredible amount of research and attention to detail in getting the story right. Lange says an assistant named Michael Jacoby would bring in 70-page binders with a history of every character. To fill in the details about Lyle and Tilly in the ’90s, Jacoby talked to people who worked with them at the shoe factory. “There was someone who saw Tilly and I in the woods getting it on, and Michael found that woman online and asked her where it happened and how it happened,” Lange says. “It was an obsessive level of culling the details and culling the research.” Not all of it can be verified, of course, and some creative license was taken and details were changed (Tilly’s real ex-husband’s name is Tobey, not Kenny, for one), but whenever possible, they leaned on the facts, Lange says. And some surprising real-life details didn’t make the show: Lyle, Tilly and Tobey and Norma all continued to work together at the factory for a time even after Lyle and Tilly moved in together. (The real Lyle Mitchell did not participate in the production, and Lange has never spoken to him. The true-to-life components of his performance, including Lyle’s distinctive teeth, are based on an interview Mitchell did with NBC. In fact, the first thing Lange did to prepare for the role was get a set of false teeth.)

Lange says that no one has recognized him from the show, and in fact, people he knows have watched the show and not realized he was Lyle — a compliment to his embodiment of the role. “And it’s a compliment to that team of people,” Lange adds. “We had just the best hair and makeup, and those teeth, and Ben’s real commitment to not let it be anything less than perfect.”

Escape at Dannemora‘s series finale airs Sunday, Dec. 30 at 10/9c on Showtime.

(Disclosure: TV Guide is owned by CBS, Showtime’s parent company.)