The Real Reason Matt Damon's Interstellar Role Was Kept A Secret

In Christopher Nolan's sci-fi epic Interstellar, the one thing you must be able to trust more than science is your team. But as fans of the auteur filmmaker know, one of the greatest elements of Nolan's style is his unreliable narrator, one thing that can make trust difficult. Nolan uses the organic tension of this narrative device not only among the characters of his Oscar-winning 2014 film but with his audience, deploying the technique right on down to the casting of star Matt Damon. 

Set in 2067, humans live in a dystopian, post-truth world where crop blights and dust storms have turned corn into the last viable crop. After former NASA pilot Joseph Cooper (Matthew McConaughey) decodes a set of coordinates scribbled in the dust of his daughter Murphy's bedroom floor, he is lead to a secret facility and eventually joins a mission to find a hospitable planet and save humanity. As the Endurance jettisons through a wormhole and land on an icy world, the crewmembers meet fellow NASA astronaut Mann, played by Damon, who's been collecting data there. Despite Mann being a pivotal part of the film, audiences had no idea Damon was cast, nor how the character's selfish desperation would help deliver Interstellar's mind (and time) bending finale. 

In an interview, the director revealed that his decision to cast Damon then keep his role a secret was about layering a twist upon a twist (via Inquirer). He compared the character to that of Kurtz from Joseph Conrad's Heart of Darkness, the novel that inspired Apocalypse Now. "You have Kurtz, this character that you hear about," Nolan explained. "Everybody says, 'Oh, he's great. Maybe you'll get to meet him.' I really love the idea for an audience to go when they see him, 'Oh, it's Matt Damon. It's going to be okay.'"

Nolan's space epic explores several themes, but its most central are about human connection and the effects of loneliness. The concept of sacrifice — intentional or otherwise — is ultimately a bridge between these two concepts. Damon's Mann wields all three in his brief appearance, manipulating data and the hopes of the Endurance crew to save himself and avoid being sacrificed for the broader mission. It's the kind of character archetype Nolan knew audiences' wouldn't expect from the star who launched his career with Good Will Hunting.

"Matt has the most amazing ability to project integrity and warmth," Nolan told Inquirer. "So he turns up in the film, and he's got a plan, and it's all going to be okay. For me, to realize that he's a frail human being and subject to cowardice and all the terrible weaknesses that we all have... he loved that challenge. I loved what he did with it."

For Interstellar producer and Nolan's partner, Emma Thomas, the decision to cast Damon wasn't just about people's first viewing, either. Because of the nature of the twist, Thomas and Nolan believed the actor's role in the film would provide viewers with a different narrative and emotional experience when they went to watch it for a second time. "If people get to watch the film twice, it's so great watching Matt when you know what's really going on," Thomas said. 

Keeping Damon's casting a secret in Interstellar was undoubtedly a classic Nolan-style move, both in terms of the narrative and for its impact on the audience. In just about every film in the director's library, whether it's Memento, The Prestige, or Inception, an unreliable narrator or character doesn't just play with the rest of the on-screen ensemble. They'll also directly influence viewers' perceptions of events, and eventually, their opinion of the film itself. 

But when it came to Interstellar, giving Damon the role and making the decision to keep it out of the film's marketing was also a practical move, according to the director. "[Matt Damon] didn't have to shoot for long. So we didn't want to market the film using him because he's not in it very much. We didn't want to mislead people," Nolan explained to Inquirer. 

In a way, Nolan and Thomas' decision prevented an unintentional twist — and possible viewer backlash — by ensuring that the A-lister's name didn't somehow end up front and center in a film where his role is pivotal to the plot, but doesn't take up much screentime. In the end, it was a secret that not only provided a great twist without misrepresenting the film, but also gave viewers a moment of reprieve in a movie that's beautifully shot and acted, but is mostly full of wall-to-wall tension. 

"Structurally, you have a lot of talk in the 20 minutes before," Nolan said. "There's a lot of negativity, a lot [of] bad things happening. The film is very much going to a dark place at that point. So getting that lift in that way with a great actor and movie star coming on screen, is a good thing."