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Viewers at early screenings of Batman v Superman: Dawn of Justice have been warned multiple times not to spoil the film for others.

Zach Snyder's film, which features Ben Affleck's Batman and Henry Cavill's Superman on screen together for the first time, is one of the year's biggest blockbusters and opens today in New Zealand.

But at a preview screening in Auckland last night, viewers received several warnings not to spoil any of the film's major events.

An email containing the invite to the film was the first warning, followed by a verbal reminder in the cinema not to spoil the events in any conversations, social media posts or emails after the screening.


Then, in a video introduction to the film by the director, Snyder issued repeated pleas not to reveal any spoilers so fans could watch the movie as it was meant to be viewed.

Finally, following the movie, an email was sent to patrons with the subject line, "Don't tell anyone".

"PLEASE NOTE that this means that all of the film's secrets now lie with you - Warner Bros. (and Zack) would like to pass on their sincerest plead with you to keep the spoilers to yourself," the email said.

"We hope you don't make them angry (remember Zack has a grumpy Ben Affleck on his side to do his bidding)."

So far, the unprecedented warnings seem to be working. Reviewers have so-far refrained from mentioning the film's biggest plot points, but that hasn't stopped them from laying into its incoherent plot and dodgy CGI.

Read more: Brutal Batfleck praised but critics say Batman v Superman is 'not fun'

"If there's any justice, dawning or otherwise, at the multiplex, audiences will reject Zack Snyder's lumbering, dead-on-arrival superhero mélange, a $250 million tombstone for a genre in dire need of a break," wrote TimeOut.

"No major blockbuster in years has been this incoherently structured, this seemingly uninterested in telling a story with clarity and purpose," said The Telegraph.

Other reviewers praised Affleck's debut as Batman and Gal Gadot as Wonder Woman, although Jesse Eisenberg's performance as Lex Luthor was criticised.

Fans also seemed to be keeping the spoilers off Twitter.

Keeping spoilers in movies intact for fans is becoming increasingly complicated for filmmakers.

During December's press tour The Force Awakens, Harrison Ford told the Herald he would prefer it if fans didn't listen to a word he said.