One audience reviewer deemed the movie “a complete disaster.” Another was “tired of all this SJW nonsense,” using the abbreviation for “social justice warrior,” a pejorative term for progressives. Yet another groused that Brie Larson, the movie’s star, “says I shouldn’t see the movie anyway.”

“Captain Marvel” had not even been released yet — its opening day was a month away — but that did not stop negative remarks from piling up against the film and Ms. Larson.

Much as Facebook and Twitter have had to grapple with false stories aimed at inciting violence or disrupting elections, movie review aggregators like Rotten Tomatoes and IMDb are often besieged by users trying to manipulate a film’s box office success.

Despite the trolls’ concerted efforts, “Captain Marvel” slayed during its opening weekend, but not before Rotten Tomatoes, an influential site where a bad audience score can damage a film’s prospects, made major changes to its rules. Most critically, it eliminated prerelease audience reviews. It also stopped displaying the percentage of moviegoers who say they “want to see” a film in favor of using the raw number of people. And it removed the “not interested” button.