A video of the gala screening shows Styles, 28, walking into the cinema to the sound of applause and taking a seat next to 42-year-old Hollywood actor Pine.
— JZMaclin (@Mac70J) September 6, 2022
Just as the Watermelon Sugar star bends to fold down his seat he appears to spit something onto Pine's lap.
The Star Trek star stops clapping, and looks down at his lap before shaking his head slightly in bemusement and breaking into an amused grin.
Styles avoids making eye contact with Pine and adjusts the buttons on his jacket, before waving a polite greeting to someone sitting further down the row.
The clip has gone viral, sparking fans to speculate if Styles did in fact spit on Pine; and if it was an aggressive move or one made in jest.
While some have speculated there may have been a bet between the two actors, others insist if Styles did spit, it was accidental.
Earlier in the day a clip of Pine had gone viral on social media at the press conference for the new movie – in which he appeared to roll his eyes and 'zone out' while Styles was talking.
The film has been plagued by controversy.
Leading lady Pugh attended the premiere, but was absent from the press conference after arriving late to the festival.
It has been reported that Pugh and Wilde clashed during the filming of Don't Worry Darling and that the Little Women star had refused to promote the movie.
Styles' role was initially played by Shia LaBeouf but he departed in September 2020 with Wilde later claiming she fired the Fury actor due to his behaviour on set.
LaBeouf, who has been accused of sexual assault by his former girlfriend FKA Twigs, recently refuted this and said he left the film against Wilde's wishes.
Wilde, 38, and Styles fell for each other during filming, and are now in a relationship.
Wilde split from husband Jason Sudeikis in November 2020. She was publicly served custody papers relating to their two children from Sudeikis while giving a presentation of Don't Worry Darling at CinemaCon 2022.
Watch: Olivia Wilde addresses Florence Pugh feud rumours