Trivia: The IMAX prints of the film are 11 miles long, weighing 600lb.
Trivia: Robert Downey Jr. declared this was "the best film I've ever been in" at the UK premiere.
Trivia: Josh Hartnett was one of the final 3 actors in the running to play Batman in Batman Begins, but withdrew. He later said he regretted his decision and wanted to work with Christopher Nolan, finally getting his chance here.
Trivia: Christopher Nolan has stated there are no shots in the movie that were entirely created using visual effects. Visual effects studio DNEG worked exclusively on the movie, and it marked the eighth collaboration between Christopher Nolan and DNEG.
Trivia: This film, combined with Barbie, became an internet phenomenon, dubbed "Barbenheimer", due to the fact that the two films were released on the same day, with some filmgoers opting to see the movies together as a double feature for no other reason than their vastly different subject matter.
Trivia: Cillian Murphy's sixth film with Christopher Nolan, after Batman Begins, The Dark Knight, Inception, The Dark Knight Rises, and Dunkirk.
Trivia: During a break from acting, promised to his wife, Matt Damon had one condition: he'd return if Christopher Nolan called. Lucky for him, Nolan offered the role of Leslie Groves, pausing Damon's hiatus.
Trivia: Alden Ehrenreich is one of the few main cast not playing a real person - his character has no name.
Trivia: This film was produced remarkably quickly for one of this scale, with only 3 months for preparation and 57 days of filming.
Trivia: Christopher Nolan's daughter, Flora, has a cameo as the girl whose skin is flaking off in Oppenheimer's vision of the effects of dropping the bomb.
Trivia: Director Christopher Nolan usually prefers using practical effects when possible. For the scene where the nuclear bomb is tested, a more manageably-sized explosion was created by a pyrotechnics team. The explosion was actually fairly close to the actors, but was filmed at specific camera angles to make it seem further away and thus bigger (a technique called "forced perspective"). Super-slow-motion was also utilized, as it subconsciously creates the illusion of a larger scale.
Trivia: This is the first Christopher Nolan-directed film since 2002's Insomnia in which Michael Caine does not appear.
Trivia: In the scene just before the Trinity test, Richard Feynman declines to use a set of welding goggles, claiming the vehicle windshield will filter out the damaging ultraviolet light. This is based on the real event, as he was likely the only person who didn't use dark glasses to witness the test.
Trivia: This is the first Christopher Nolan film since 2000's Memento not to be distributed by Warner Bros. Nolan's partnership with the studio soured over his dissatisfaction with their decision to release new films on HBO Max on the same day as their theatrical releases during the height of the COVID-19 pandemic.
Answer: The short version is "no, not really". Much like in the film, the possibility was considered, a lot of calculations were done, and it was agreed by everyone privy to them that the chance was basically zero. Also like in the film: "what do you want from theory alone?" - it couldn't be guaranteed to be absolutely zero, but then the chance of almost anything happening is never absolutely zero. A 1946 report by three of the scientists stated: "whatever the temperature to which a section of the atmosphere may be heated, no self-propagating chain of nuclear reactions is likely to be started. The energy losses to radiation always overcompensate the gains due to the reactions."