You’re at a movie, ready to enjoy Hollywood’s latest blockbuster. You know the best actors, directors and screenwriters have worked together to entertain you.

What you probably don’t know: China’s Communist Party may have forced the studio to replace characters, change or omit visuals, even alter the entire plot.

If you publish something in China, the government censors it. Every newspaper, every television show, even your personal social media posts — all can be suppressed. Even movies made in other countries.

China’s censorship rules are vague and inconsistently enforced. Anything deemed anti-China can be banned. So can content that violates a censor’s view of desirable social morality or which the censor decides somehow goes against China’s interests.

China’s censors force movie studios to change details, alter characters, and rewrite major plot points.

“Beijing routinely demands that Hollywood portray China in a strictly positive light,” Vice President Pence said in a speech last year. Beijing is “taking steps to exploit its economic leverage and the allure of their large marketplace to advance its influence” over businesses.

What does Chinese censorship look like? For starters, if your script includes Tibet or Taiwan, be prepared to rewrite it, or find your movie banned in China. In the 1986 movie Top Gun, Tom Cruise’s character wore a leather jacket with patches showing the flags of Japan and Taiwan. In images released from the upcoming sequel, fans noticed the patches are no longer there.

Fans of Marvel’s Dr. Strange comic books were similarly surprised to learn that the Ancient One, a Tibetan character first introduced back in 1963, had somehow become Celtic in the 2016 movie.

Thanks to China, the Ancient One’s now Irish.

“If you acknowledge that Tibet is a place and that he’s Tibetan,” a writer said on a culture podcast, you “risk the Chinese government going, ‘Hey, you know one of the biggest film-watching countries in the world? We’re not going to show your movie because you decided to get political.’”

And, the Los Angeles Times reports, Chinese flags were digitally replaced with North Korean ones in the 2012 movie Red Dawn.

“MGM has been working with the film Red Dawn’s director and producers to make the most commercially viable version of the film for audiences worldwide,” Mike Vollman, MGM’s executive vice president of worldwide marketing, told the L.A. Times.

The Communist Party “punishes studios and producers” that don’t portray China in a positive light, Pence said. “Beijing’s censors are quick to edit or outlaw movies that criticize China, even in minor ways.”