This post contains spoilers for The Walking Dead Season 7 premiere.

Fans are still reeling from the loss of Glenn (Steven Yeun) and Abraham (Michael Cudlitz) in The Walking Dead's season premiere, but what's even more eye-popping (sorry) than the deaths themselves is the logistical wrangling that went into filming them.

On Sunday'sTalking Dead, showrunner Scott Gimple admitted that the plan to kill Glenn and Abraham had been in the works for around two years -- and the cast members had been keeping that secret for over a year.

SEE ALSO:Recap: 'The Walking Dead' finally reveals who Negan killed, and we're not okay

How did the series -- which has fallen prey to numerous plot leaks over the years, thanks to spoiler-hungry fans seeking out the set -- pull off two huge twists without anyone finding out? Executive producer Greg Nicotero told reporters exactly what went into the gargantuan task during a conference call Monday.

"It’s unfortunate that there are people who are dedicated to ruining the experience for others, but we did shoot some alternate [takes] and we did shoot some other characters," Nicotero explained, pointing out that Rick's visions of every group member potentially being hit with the bat helped the producers maintain the secrecy of the deaths, since everyone was filmed on the receiving end of Lucille.

"That was a great device to really help get into Rick’s head as he’s imagining the horrific act happening over and over and over again -- [and] it didn’t hurt to put that out there ... to preserve the experience, because that’s first and foremost what we wanted to do," said Nicotero.

Andrew Lincoln as Rick GrimesCredit: AMC

Some fans and critics have accused the show of being manipulative in making the audience wait 20 minutes to find out who Negan's victims were, but Nicotero defended that choice.

SEE ALSO:You can be mad about that 'Walking Dead' death, but you shouldn't be surprised

"It certainly wasn’t intended that way. When you step back and look at the episode, what you realize is, the majority of it is from Rick’s point of view, so picking up moments after the death and going into the beginnings of Negan trying to break Rick, Negan realizes that what he’s just done didn’t do the trick, so the episode is really about Negan’s efforts [to break him]," he explained. "The episode is 100 percent designed for you to go on this journey with Rick and start thinking, as he did, about what happened. When he starts reliving it, it’s the beginning of him being broken, and by the end of the episode, that’s where he ends up."

Nicotero admitted that more than anything, he wanted to stay true to the spirit of issue 100 of Robert Kirkman'sWalking Dead comic, in which Negan killed Glenn.

"It’s intense and a lot of people that read the comic books and read the graphic novel, these moments have been ingrained in their brain," he said. "I remember sitting next to Steven when I read issue 100 and talking with him and Robert about it. What struck me about it was, it was horrifically graphic and senseless and brutal, and I wanted to try to capture those moments."

Mashable Top StoriesStay connected with the hottest stories of the day and the latest entertainment news.Sign up for Mashable's Top Stories newsletterBy signing up you agree to our Terms of Use and Privacy Policy.Thanks for signing up!

The brutality of Negan's actions were designed to emphasize just what a formidable foe he is, according to Nicotero. "In this instance, we felt that it was important to launch us into the season by showing the extent of what Negan is capable of doing because that drives so much of where the series is going from here on in, and the opportunity to introduce all the new worlds."

In addition to directing the episode, Nicotero is also in charge of the show's Emmy-winning visual effects, which meant he designed the makeup and prosthetics that transformed Glenn and Abraham's heads into bloodied stumps.

"The deaths were very difficult to film, but from a technical aspect, we had multiple stage prosthetics and multiple makeups on both characters," he said. "For me, the most significant thing was the bat that I designed that had a reservoir of blood, and how we were able to get the hits to look explosive as opposed to just blood dribbling."

While losing two beloved characters was understandably emotional, Nicotero admitted that given the technical difficulty of the death scenes, everyone was focused on getting it right, which made it easier for the cast and crew to stay detached.

SEE ALSO:'Walking Dead' boss admits he was trying to break you with the Season 7 premiere

At certain points during Negan's beating, it was hard for viewers to tell what was real and what was makeup, but Nicotero said that Glenn's twitching fingers were all Yeun.

"With Steven, we built multiple versions of that prosthetic where the eyeball popped out and then when he’s on the ground and the head is crushed, we actually dug a hole and put Steven’s face down into the ground and covered the back of his head with this kind of turtleneck crushed head, so that you could see his real hands twitching and moving as he started pumping blood," Nicotero said.

The toughest part of filming the death scenes for Nicotero was keeping everyone in such a heightened state for so long: "The emotion was there because the actors are so talented and so dialed in and I really feel like Andy Lincoln gave the performance of the series in this episode. As the director it was up to me to drag these people into this deep, dark place and it was not the most pleasant experience. When we wrapped the episode I felt as shellshocked as some of the characters in dealing with that."

When Negan wins, everybody loses.Credit: amc

The morning after scene was "more challenging and emotional" from Nicotero's perspective: "When Maggie gets up and walks over, and Sasha gets up, that’s the morning-after moment," he noted. "The death scenes were definitely challenging to shoot, but because there was so much technical stuff from my end, I think we were a little more focused on how to to make it look as authentic as possible. Because those quick snippets will remain in the audience’s and our characters’ minds for several seasons and months and years to come."

The two deaths have resulted in plenty of anger and frustration online, but the producers are standing by their decision.

"If you didn’t feel anything, we would’ve been in big trouble," Nicotero said. "It’s not the deaths that really catapult you; the deaths are shocking, and you react to the deaths in this 'I can’t look anymore, I have to turn away' fashion. But truthfully, it’s those moments after, it’s when the shock wears off and Rick is broken, the pure and true emotion happens in the last couple acts. I’ve spent so much of my career understanding and dissecting the technical aspects ... to be able to elicit the emotion that I can from these actors, to me, that’s the success of the episode."

The Walking Deadairs Sundays at 9 p.m. on AMC.

TopicsThe Walking Dead