Forty-two years after "Star Wars" first took fans to a galaxy far, far away, director J.J. Abrams said the final chapter of the epic series is finally finished.

Abrams joined "Good Morning America" Monday and said the team officially finished post-production of "Star Wars: The Rise of Skywalker," "just yesterday."

"This happened last time as well," he said, referencing "The Last Jedi." "You see something and you think that could be a little clearer, a little better and if you have the ability to fix the piece, you take advantage of that."

Abrams added that bringing the decades-long journey to a finale was frightening.

"Part of it was scary because I care about it so much. Part of it was it's an ending not of three films, but nine films and it means a lot to a lot of people, us included," he said. "We felt the pressure but the opportunity was always greater than the challenge."

The director, 53, said one of the greatest opportunities was their ability to utilize unused footage of the late Carrie Fisher, who played the iconic Princess Leia, in order to incorporate her character one last time.

"It was impossible for us to figure out how to tell the end of the Skywalker saga without Leia. She's such an important character, and Carrie, we needed to have her in the movie," he prefaced. "We realized there were probably five or six scenes that we never used and we went back and looked at the footage and realized we could tell the story, create scenes with her, but we did it in a really interesting way where we used her footage and everything in the scene was written around, built around, lit around what we had of her."

Abrams added some of Fisher's new scenes "are really moving and it's impossible for me to believe she's not there."

"We've been working with her in the editing room for almost a year and she's vital and she's there and she's funny in spirit. She's Leia in this movie. It's sort of surreal," he said.

Abrams said the security efforts to keep this film under lock and key was "insane," but revealed there was a hiccup behind the scenes with one of the scripts.

Without revealing who, he said one of the actors "left it under their bed and it was found by someone who was cleaning their place and it was given to someone else who then went to sell it on eBay."

"Someone at the company said there's a script that looks like it's a legit script that's for sale on eBay," Abrams said. "They got it back before it sold."

Ahead of the movie's big debut, Abrams added that he's "grateful" for the level of interest and care people have reading into even the smallest details.

"The key to doing a movie like this -- you want to make sure the details have meaning and matter because you know that they're going to be scrutinized," he explained.

A new exclusive trailer for the movie debuted on "GMA" and revealed for the first time, stormtroopers could take to the sky.

In the clip, the iconic white-suited soldiers soared overhead, much to the surprise of C-3PO, Finn and Poe Dameron as they try to escape.

"Star Wars: The Rise of Skywalker" is in theaters nationwide on Dec. 20.

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