There's a historical error in the American flag featured in 'Oppenheimer,' and people are taking to Twitter to call Christopher Nolan out for it

• Eagle-eyed movie-goers have taken to Twitter to call out a historical error they spotted in "Oppenheimer."
• American flags with 50 stars were used in a scene where a crowd surrounds Cillian Murphy's character.

Christopher Nolan is known for being a perfectionist, but it seems that he might have missed an important detail in his latest film "Oppenheimer."

Eagle-eyed movie-goers have taken to Twitter to call out a historical error that they spotted in the movie, which opened in theaters on Friday, July 21.

On Saturday, Twitter user Andy Craig, who goes by the username @AndrewRCraig, pointed out a scene from the movie where a cheering crowd gives Cillian Murphy's "Oppenheimer" character a standing ovation.

"It was good and all, but I'll be that guy and complain they used 50-star flags in a scene set in 1945," Craig wrote in his tweet.

In this particular scene — which is set in 1945 — members of the crowd can be seen waving American flags with 50 stars — which was only established more than a decade later in 1959, under President Dwight D. Eisenhower.

In 1945, under President Harry S. Truman, the US flag only had 48 stars because it was made up of 48 states — excluding Alaska and Hawaii.

Craig's tweet sparked a flurry of replies. Some agreed that they had caught the mistake too, while others poked fun at the minor mishap.

One tweet responded by saying "That's an amazing 'catch.' Now I'll never 'not' see it."

Another pointed out that the correct 48-star flag was used elsewhere in the film.

Another Twitter user, also made the case that the wrong flag was used intentionally since it appeared in a colored scene — which would be based on Oppenheimer's present-day perspective.

Insider previously reported that the "Oppenheimer" film switches between scenes in color and scenes in black-and-white to represent the same events through different perspectives.

Universal Pictures did not immediately respond to a request for comment sent by Insider outside of regular business hours.