Robert De Niro and his co-stars in "The Irishman" were able to step back in time thanks to a new digital de-aging process used in the film.
The effects make the actors appear years younger. De Niro talked to ABC News about how it all worked.
"They wanted to make it the best that it had ever been to date," De Niro said in an appearance on "Popcorn with Peter Travers." "And that was exciting for me, for us, knowing that they were going to do the best that they can and hopefully we got close to that point."
He added, "Marty (Scorsese) was concerned about having all sort of gadgetry on us, helmets and this and that which would be a distraction for the actors. So it was pretty simple. We had a bunch of reflecting kind of things on our jackets and imperceptible dots on our face."
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(MORE: Joaquin Phoenix on the making of 'Joker')De Niro stars opposite other acting greats Al Pacino and Joe Pesci in the crime story based on the 1975 disappearance of labor union leader Jimmy Hoffa.
In the film, 76-year-old De Niro plays 46-year-old mafia hitman Frank Sheeran. Travers asked the legendary actor if it was difficult to mimic the movements of a much younger version of himself.
"I didn't feel that my physical movements were as aged as someone may suspect or think or see," he said. "You feel your age, but not the way people would think that you'd feel it. If you try and stay in shape and stay active it can minimize all those age-like things."
While this is his ninth film with director Scorsese, it's been some 20 years since the two worked together.
"We wanted to work together earlier. Marty wanted me to be in "Gangs of New York." But that was hard because it was shooting in Italy, meaning I'd spend a lot of time away from the city and I couldn't do that at that time. I was very disappointed I couldn't. Daniel Day Lewis did the part that I was going to. He was great in it."
"This is great, me, Al (Pacino), Joe (Pesci), Marty (Scorsese) directing -- this project, it'll be special. But if it's received in a special way that's even better," he added.
"The Irishman" can be seen on Netflix.
Be sure to watch the full interview with Peter Travers and Robert De Niro in the video above.