The film world approaches its awards season, and is experiencing a recurrent phenomenon concerning the way press promotional comment becomes dangerously unhelpful and unmanaged. The errant publicity takes up as much cultural space as the film, a distracting alternative narrative. It is cognitive hype dissonance.

Robert Zemeckis’s forthcoming Allied is set fair to be a great big blockbuster, a swooning second world war romantic drama. Brad Pitt is Max Vatan, a handsome Allied intelligence agent who has a steamy affair with French resistance fighter Marianne Beausejour, played by Marion Cotillard. But then he is told that she is a Nazi spy and he must kill her. It sounds like a gripping tale, full of passion, transgression, suspicion.

The problem is that the public, disobediently giggling over their social media accounts, reckon they’ve already got the scoop without needing to see the film. As reports came in of Brad’s upcoming divorce with Angelina Jolie, fans convinced themselves he had been cheating on Ange with Marion Cotillard while away shooting this very picture. Mischievous bloggers and tweeters are jujitsu-ing the Allied publicity machine with gags about how it’s Ange who is going to come on to whack Marion. Allied might be upstaged by the gossip, and become best known for something other than itself.

And why shouldn’t it happen? Cotillard and Pitt have denied any affair, but the rumours have been fuelled by how Pitt and Jolie first met. When the couple were filming Mr and Mrs Smith a decade ago they were married to other people. The film ignited their romance. The publicity worked in the film’s favour, just about, though with lingering sympathy for Jennifer Aniston. This kind of spontaneous fact-meets-fiction hype mirage is hardly new. Richard Burton and Elizabeth Taylor met while filming Cleopatra in the late 1950s, and both were married. Their affair was considered hardly less sensational and world-historically important than that of the characters they played.

A quite different, more serious sort of publicity dissonance concerns The Birth of a Nation, the forthcoming true-life story of a US slave uprising in 1831, led by Nat Turner, played by the movie’s young director Nate Parker — and of course satirically named after DW Griffith’s notorious silent movie of 1915 praising the Ku Klux Klan.

Before anyone had seen the film, they had read about how it had stunned crowds at Sundance and secured a huge studio deal. In the #blacklivesmatter era, this was a movie the liberal media classes were naturally preparing to get behind, until it became known that Parker had been accused of raping a fellow student while at Pennsylvania State University in 2001; he was acquitted. The complainant later took her own life, in 2012. It should be irrelevant to the question of how good the film is. But it can hardly be set aside, especially for a film with lofty ideals.

The news story looms over the film. How to reconcile the two? Richard Brody in the New Yorker boldly tackled the dissonance head on with his comment about the way Parker shows the rapes in his movie. They are “depicted entirely from their significance to men,” Brody writes. “Parker appallingly shifts the scenes around to the male view of the action, and never shows women in discussion among themselves, never presents how enslaved women endure and confront their own oppression.”

Counter-reading … Nate Parker in The Birth of a Nation, about a US slave uprising. Photograph: Jahi Chikwendiu/AP

A similar kind of real-life counter-reading has been happening for decades with Roman Polanski’s films, to which the director has long made it silently plain he will not concede an inch. Time will tell if Parker must pursue the same course, although their legal positions are different.

These cases are quite different from the phoney stories planted by studio flacks from time immemorial, dependent on co-operative artists and a complaisant press. Fixers from the Hollywood golden age like MGM’s Howard Strickling and Eddie Mannix and Fox’s Harry Brand were always creating bogus romances, fake intrigues and hokey life-stories to promote movies or distract attention from brewing scandals. The Coens’ Hail Caesar! (2016) and Alexander Mackendrick’s Sweet Smell of Success (1957) have scenes about this seedy byproduct of the fantasy-factory.

Press rows sometimes dwarf their films and sometimes they don’t. Before Doctor Strange was released, there was widespread unease about the portrayal of the Ancient One, regendered and reconceived for the movie and played by Tilda Swinton, with a “Celtic” origin. Was the Tibetan identity erased out of deference to the important Chinese market? Very possibly. As things turned out, her weirdness seemed to go beyond national identity.

Will change film-making for ever (or not)… Samuel L Jackson in Snakes on a Plane Photograph: New Line/Everett/Rex Features

Or take a movie that was once the most discussed film of its day, a film which the commentariat regarded with saucer-eyed seriousness as a zeitgeist phenomenon: Snakes on a Plane (2006). It is difficult to believe now, but this all-but-forgotten Samuel L Jackson thriller about — well — snakes on a plane, was once feverishly discussed, because of its much-vaunted but wildly exaggerated status as an internet phenomenon. The producers allegedly incorporated online feedback into production with extra shooting days. Pundits believed that this Wiki-ised technique could be used for all films from then on. But it wasn’t. And when the film turned out to be a bit of a dud, this wall of chatter turned to sheepish silence.

The list of dissonant films goes on. The Interview (2014) was a film satirising North Korean leader Kim Jong-un that led to hacking attacks, which in turn led to apparently craven industry moves to re-edit the film and limit its distribution. The resulting hype built the movie up in everyone’s mind as a classic of satire, standing up heroically to both the North Koreans and the cringing producers. When it finally came out, it was clear that it wasn’t that great. It didn’t fit the narrative created for it.

Not the disaster everyone said it would be … Titanic. Photograph: Allstar

Other films have identities which leaked into the real world of the news: the Watergate mole took his nickname from the title of the porn film Deep Throat (1972). It wasn’t simply arbitrary. In the Watergate era, when cynicism about a dodgy president was becoming widespread, there was a kind of weird karmic alliance between this blase mood and the new porno chic.

Very strangely, in recent times, there has been an attempt to force this kind of branding. In the runup to the Brexit vote, Boris Johnson was bellowing that the referendum would be “independence day” — apparently attempting to coattail the publicity of the sci-fi movie sequel with that name. Brexit was victorious, but no-one remembers Boris’s cheery, lame film-title wheeze.

The strangest example of publicity dissonance was that which accompanied the release of James Cameron’s gigantic blockbuster Titanic (1997). Of course, this is remembered as a colossal triumph, which involves a willed amnesia about the huge groundswell of stories before its release about the impending opposite: how terrifyingly unsafe the production was and how brutally Cameron had been driving his cast. There were stories about how Kate Winslet had chipped a bone in her elbow during filming and how she seriously thought she might drown in the tank in which the “sinking” scenes were filmed. The narrative was clearly all about how the curse of Titanic was about to strike again …. But it all vanished like snow off a ditch when the film emerged and became a hit.

Allied is in cinemas from 23 November

• This article was amended on 7 November 2016 because an earlier version wrongly said Tilda Swinton’s scenes in Doctor Strange were shot in Tibet; they were shot in Nepal.