Matt Damon broke a promise to his wife to work on Oppenheimer

During the film’s casting phase, Matt Damon was on hiatus from acting, fulfilling a promise he had made to his wife. However, he stipulated that if Christopher Nolan reached out, the break would have to be suspended. When Nolan extended an invitation to portray General Leslie Groves, Damon took it straight away, marking a swift end to the hiatus.

Robert Downey Jr. took a reduced salary to star in the film

Robert Downey Jr. demonstrated his commitment to the project by willingly accepting substantial pay reductions to portray Lewis Strauss in the film. Notably, Downey himself has praised Oppenheimer as the pinnacle of his acting career, saying it is the best movie he has ever been a part of.

Josh Hartnett wasn’t going to snub Christopher Nolan again

Around two decades prior to Oppenheimer, Josh Hartnett declined Christopher Nolan’s offer for the role of Batman in Batman Begins. In hindsight, he expressed remorse for this decision. Consequently, when Nolan extended the opportunity to portray physicist Ernest Lawrence, Hartnett wasn’t going to make the same mistake twice and eagerly accepted Nolan’s offer.

The Einstein and Gödel scenes are based on factual events

In scenes many could have believed was artistic licence by Nolan, Albert Einstein, portrayed by Tom Conti, walks with Kurt Gödel in the woods. Surprisingly, this is rooted in truth, as the real Einstein and Gödel often strolled together at the Institute for Advanced Studies.

A small mistake with the American Flag can be found in the movie

During Oppenheimer’s victory speech, Los Alamos residents wave American flags adorned with an inaccurate number of stars. Although the film displays flags with 50 stars, suitable for the present day, in 1945 the flag should have had just 48 stars, as Alaska and Hawaii had not yet achieved statehood.

Practical effects were used in the movie rather than GCI

Nolan really wanted to make the film without CGI. In the Trinity detonation scene, a combination of practical effects and digital compositing is employed. Several gasoline and propane explosions were executed, alongside miniature town models. These actions were recorded at high speeds, and digital techniques were used to make the mushroom cloud.

Scenes were filmed in Oppenheimer’s real life home

Segments of the movie were filmed within Oppenheimer’s authentic cabin in New Mexico, which had been previously renovated for incorporation into the Los Alamos national park. Originating in 1929, the Oppenheimer residence initially catered to the Los Alamos Ranch School until its repurposing for the Manhattan Project.

Nolan cast his own daughter in one of the most harrowing scenes

Photo by Lia Toby/Getty Images for Universal Pictures

In the scene where Oppenheimer is confronted by harrowing visions of bomb victims, a young woman can be seen with skin peeling off her face. This woman is played by Nolan’s own daughter, Flora. The idea to cast her came to Nolan after his daughter accompanied his wife, Emma Thomas, to set one day.

It’s Nolan’s first R-rated movie since Insomnia

Nolan’s lesser recalled 2002 work Insomnia, featuring Al Pacino and Robin Williams, marked his final venture into R-rated filmmaking. However, after a span of two decades focused on PG-13 projects, Oppenheimer received an R rating from the Motion Picture Association of America due to some sexuality, nudity and bad language.

Oppenheimer sees Nolan work without Warner Bros. for the first time

After his involvement in 2000’s Memento, Nolan’s subsequent films were consistently co-produced with Warner Bros. Pictures. Nevertheless, a rift developed between the director and the studio when they opted to shift their 2021 film line-up to HBO Max. Consequently, Oppenheimer marks Nolan’s inaugural collaboration with Universal Pictures.