Now that the Barbenheimer era is in full swing following the releases of Barbie and Oppenheimer this weekend, film fans who flocked to see both movies already have issued a stark warning to cinemagoers.

Although the two films could not be more different in tone; one being a biographical thriller about the creation of the atomic bomb, the other a fantasy comedy about a plastic doll - there's one thing they have in common, and that’s that people have been very excited for their arrival because they shared a release date.

Universal Pictures

Now, eyeballs across the world have been glued to the big screen as fans followed-through with their pledge to watch Christopher Nolan’s Oppenheimer and Greta Gerwig’s Barbie back-to-back.

Oppenheimer is based on the 2005 novel American Prometheus by Kai Bird and Martin J. Sherwin.

The book and the film adaptation follow the story of real-life physicist J. Robert Oppenheimer, played by Cillian Murphy, who is working alongside a team of scientists to build the world's first atomic bomb during World War II.

Meanwhile, Barbie stars Harley Quinn actor Margot Robbie as the titular doll alongside Ryan Gosling's Ken.

The official synopsis says: "After being expelled from Barbieland for being a less than perfect-looking doll, Barbie sets off for the human world to find true happiness."

As you can probably tell, the two movies are worlds apart in tone but that hasn't stopped cinemagoers from treating them like an unofficial double feature.

However, those who have seen both flicks have taken to social media to warn fans about the correct order to watch them, with people urging the world not to watch Oppenheimer before Barbie.

"WARNING: Do NOT watch Oppenheimer before Barbie," one viral tweet reads which has been viewed over 11 million times. The Twitter user used a picture of a disheveled Ryan Gosling from his 2016 film The Nice Guys.

Twitter/@joshtenet

Countless movie fanatics agreed, with one person responding: "If u haven’t watched them yet then def watch Barbie first, u will feel empty after Oppenheimer."

Another commented: "Did y'all like... forget the subject matter of Oppenheimer."

One Twitter user shared a GIF of The Weeknd running through a corridor and wrote: "Trying to get out of the cinema and past the crowds while I could still hear and see explosions in my memory."

Although some people are just straight-up ignoring the warning, with one person declaring they're watching Oppenheimer first.

"I’m about to do this I’m so f**king pumped," they wrote.

Another rebel penned: "Absolutely watch Oppenheimer before Barbie."

If there was ever a time when you need the internet to agree on something, it's now.