Jimmy Kimmel dumbfounded as movie stars crash his monologue: 'Can I help you?'

"Can I help you?"

That was the question that late-night host Jimmy Kimmel asked Margot Robbie as she glided through his "Jimmy Kimmel Live!" set to go to the premiere of her new film, "Once Upon a Time in Hollywood."

The actress was the first of three of the film's stars to walk through Kimmel's monologue filming during Monday night's episode, resulting in a hilarious segment that has already gone viral online.

SEE ALSO: All of the glam red carpet looks from the 'Once Upon a Time in Hollywood' premiere

Next was co-star Brad Pitt, who told Kimmel he was "just cuttin' through" on his way to the premiere across the street.

"I get it, but, I just want to say, this is not just some kind of an alleyway," Kimmel told Pitt.

Last it was Leonardo DiCaprio, who was making his first ever appearance on Kimmel's show. When Kimmel confronted the Oscar winner about what he was doing, he said that he was there to deliver an epic surprise to the adoring studio audience, who went crazy for his reveal.

Watch the full moment in the clip at the top of the page.