Robert Redford as Superman? 5 highlights from the new Christopher Reeve documentary

As the three children of the late Christopher Reeve stood in front of the first few hundred people who had just viewed a new film about their dad at the Sundance Film Festival , they were visibly proud.

In their eyes, " Super/Man: The Christopher Reeve Story " did their father's story justice, showing how the actor went from being a relative unknown to an on-screen superhero to a real-life hero as he became a public face for disability research and activism .

"It matters to show that it was hard sometimes but that there was overwhelming joy at the same time," Alexandra Reeve said during the Q&A following the Sundance screening, as the Deseret News previously reported. "It mattered to us that this was an authentic film, that this wasn't shown through rose-colored glasses."

Now, following its emotional premiere in Park City, Utah, "Super/Man" is hitting select theaters on Sept. 21 and Sept. 25 (which would've been Christopher Reeve's 72nd birthday).

Here are five highlights from the documentary.

Robert Redford was considered for the role of Superman Robert Redford was apparently considered for the role of Superman in the early stages of production — a fact that got a few laughs from the crowd during the film's premiere at Sundance, which was founded by Redford. Other A-listers who were in the running included Burt Reynolds, Paul Newman, Arnold Schwarzenegger and Neil Diamond.

In the end, though, producers opted to go with a relative unknown. They landed on Reeve, a theater kid who wound up studying at The Juilliard School. He was 24 at the time.

When Reeve got the part, his father — an academic who didn't always approve of his son's career — was initially excited because he thought Reeve was starring in the George Bernard Shaw play "Man and Superman."

Superman would become Reeve's defining role, but he never wanted to be simplified to one character, according to the documentary. He wanted to reinvent himself as an actor.

Following his accident in 1995, when he was thrown from his horse and paralyzed from the neck down, Reeve underwent a different kind of reinvention — one that drew on the lessons of his acting career.

"When he had the accident, he actually was on the floor, had to learn to speak again, couldn't do anything on this own," director Ian Bonhôte told the Deseret News ahead of the film's first screening at Sundance. "And he harnessed the power of Superman."

Christopher Reeve's relationship with Robin Williams Reeve's friendship with late actor Robin Williams is a recurring — and really moving — theme throughout "Super/Man."

The pair first met as classmates at The Juilliard School. Williams was one of the first people who visited Reeve in the hospital following the accident, and he pulled a prank on Reeve by posing as his doctor. It was one of the first times Reeve laughed since his injury, and the realization that he could still laugh gave him hope.

In the documentary, as the Deseret News previously reported, actress Glenn Close recalls the special friendship between Williams and Reeve, saying that they were both "aware of darkness" and knew how to lift each other's spirits.

"I've always felt if Chris was still around, then Robin would be alive," she said.

When Christopher Reeve made a surprise appearance at the Oscars One of the most emotional moments in "Super/Man" comes during a clip that shows Reeve's surprise appearance at the 1996 Academy Awards — which took place less than a year after his accident.

Reeve's plan to attend had been kept under wraps in case it didn't work out due to logistical reasons or a medical emergency, but as the curtain came up to reveal Reeve at the center of the stage, the love and admiration his fellow actors had for him was palpable.

A long, tear-filled standing ovation greeted him, with everyone from Nicolas Cage to Jim Carrey to Tom Hanks clapping for well over a minute. Williams could barely keep his composure.

"What you probably don't know is that I left New York last September, and I just arrived here this morning," Reeve joked. "And I'm glad I did, because I wouldn't have missed this kind of welcome for the world."

Dana Reeve's enduring love Throughout its 1 hour and 45 minute runtime, "Super/Man: The Christopher Reeve Story" attempts to define heroism. Ultimately, it reaches this conclusion: "An ordinary person who finds strength to endure despite overwhelming obstacles."

While that certainly applied to Christopher Reeve, it also applied to Dana Reeve, whose love and care for her husband during the last nine years of his life embodied what it means to be a hero.

It's clear throughout "Super/Man" that Reeve's greatest source of strength was his wife, whose initial words to him in the hospital following the accident helped quell his fears and doubts: "You're still you, and I love you."

As Reeve's three children attest in the documentary, Dana Reeve was the glue that kept the family together through all the ups and downs, even as she worked through her own pain.

"I have been studying the difference between solitude and loneliness. Telling the story of my life to the clean white towels taken warm from the dryer and held to my chest. A sad substitute for a body pulled in close," reads an excerpt from Dana Reeve's journal, read by her son Will Reeve, in "Super/Man." "I think of him in certain lights. Dawn, late afternoon, bright windy days that would be perfect for sailing. I miss most even now his hands. The expressive grace and heft of them. The heat of his hands on my skin. The wrap of his arms, two becoming one. I carry the stack of towels upstairs carefully cradling them so as not to let them tumble. Save one still damp, the top one I had pressed against my face, which needs more time for drying."

The vulnerability of Christopher Reeve's children The film draws heavily from raw interviews with Reeve's children, archives and home videos.

In one present-day interview, Reeve's oldest child, Matthew Reeve, is visibly moved as he recalls how his father was getting ready to leave for a weekend but turned around at the front door to wave goodbye one last time. That would be the last time he saw his father stand on his feet.

All three of Reeve's children open up about adapting to a new lifestyle with their father following the accident. They also speak of the love they have for Dana Reeve, who died less than two years after their father following an unexpected lung cancer diagnosis.

With emotion, Alexandra Reeve recalls Dana Reeve shouting "I love you" over and over as her husband passed.

Will Reeve, who is the youngest of the three children and the only child of Christopher and Dana Reeve (Alexandra and Matthew are his half-siblings), reflects on how he was 13 when he lost both of his parents and how "alone" he felt, even as he was surrounded by the support of his siblings and his adopted family.

"We wanted this project to be the definitive story of our dad's life, and that requires an emotional ride," Will Reeve told the Deseret News ahead of the film's first screening at Sundance. "And we were prepared for it, as much as one can be."

"To see it well told has really just been such a gift," he later said during a Q&A following the first screening. "When we get to watch this movie, we get to have another couple hours sitting with our parents. I got to hear dad say 'Good morning sunshine' one more time today, and that's really special."