Robbie told ET that there was one line while on set that she wasn't expecting from her co-star.
Talking with ET's Rachel Smith on the red carpet of the Gotham Awards, Robbie, 33, said Gosling's line in the film's third act in which his character emphatically yells out "sublime" to this day still makes her laugh.
"It's tricky because watching it on screen is one thing, but being there for the scene was a different thing," she said, responding to the question of which scene is her favorite from the 2023 blockbuster.
"The one that I always -- It was one line that Ryan improvised on the day. When he yells out 'sublime.' I wasn't prepared for that, that wasn't in the script and to this day, that makes me laugh," the actress continued.
In the scene Robbie is describing, her character is approaching Ken at his "mojo dojo casa house" to seemingly accept the offer of becoming his "long-term, long-distance, low commitment casual girlfriend." Ken asks Barbie to excuse him for a moment which is when he takes the opportunity to excitedly yell out "sublime" at what he thought was a win.
What's more, in the recently released behind-the-scenes video from the film, Gosling, 43, can be seen giving it his all in the first take of the scene, causing his co-star to break character and eliciting a gaggle of laughter from behind the character.
Due to the 118-day SAG-AFTRA strike, actors were unable to discuss their projects in accordance with their union's guidance, meaning that many are just now being asked about their films and TV shows that premiered over the summer and in early fall.
Robbie also said that despite her black ensemble for the Gotham Awards, there "may be some pink left in the closet" still as the days inch closer to the Academy Awards in February.
Even without an ounce of pink on her, the actress was still referencing the iconic doll that she brought to life on the big screen earlier this year.
Eagle-eyed fans on social media quickly noticed that the black dress, translucent cape, gloves, gold clutch and hairstyle sported by the Australian-born actress were a nod to the 1964 "Black Magic Barbie."
ET asked her about how she is feeling about the film's chances at the Oscars, which she said would be monumental for the cast and the crew.
"If Barbie goes to the Oscars, that would be quite historic in my mind," she said. "That would be incredible."
As of late November, Variety predicts Barbie will receive nominations in the categories of Outstanding Adapted Screenplay, Outstanding Director, Outstanding Film and more.