The film charts the life and career of J. Robert Oppenheimer, the American scientist who oversaw the invention of the world’s first nuclear weapons during WW2.
One scene set in 1945, sees Oppenheimer (played by Cillian Murphy) give a speech after the bomb’s successful test run at the then-top secret Los Alamos laboratory.
As ‘the father of the atomic bomb’ makes his way through the crowd, his fellow scientists and their families can be seen celebrating with American flags.
However, as eagle-eyed fans have pointed out on Twitter, the flags shown in the film feature 50 stars – two more than it really had at that time.
Alaska and Hawaii did not officially become US states until 1959, which is when the flag was changed to look as we know it now, with 50 stars instead of its previous 48.
Some fans did offer a possible explanation for the decision:
Oppenheimer has proved a huge hit with critics, who praised its “laser-sharp” script while calling for the film and its cast to land Oscar nominations.
Early figures revealed the film has given director Nolan his biggest opening weekend numbers for a non-Batman movie, taking a whopping $174.2m (£136m) worldwide.
Meanwhile, Barbie celebrated the highest first weekend takings ever for a film by a female director and surpassed The Super Mario Bros. Movie to land the biggest opening weekend of the year.