SLIGHT DOCTOR STRANGE SPOILER ALERT: Not only does Cumberbatch mention the music superstar in Doctor Strange, but we even get to hear a little of her music in the superhero flick.
And guess whose idea it was to throw her into the movie?!
"It was improvised," Cumberbatch says while crediting himself with the ad lib. "It was a lot of fun." (You'll have to see the movie to see exactly what happens.)
Also a lot of fun while shooting the movie? When Cumberbatch brought his baby son Christopher to set.
"It was wonderful and that was a nice way to have a moment or two [with him] because it was a very, very busy schedule as you can imagine," said Cumberbatch, whose wife Sophie Hunter is now expecting their second child.
It sure was busy.
Not only was he a first-time dad while making the movie, but Cumberbatch was also performing Hamlet on the London stage every night for three hours.
His Doctor Strange workouts and diet came in very handy. "I needed to be on top of my health and thank god for having that kind of bedrock of the trainings," Cumberbatch said.
And yes, there's even a shirtless shot of the muscled-up Cumberbatch in the movie. "All superheroes have to have something going on under their costumes," he said.
Doctor Strange follows a surgeon named Dr. Stephen Strange who gains superpowers when he visits a mystic (Tilda Swinton) after his hands are destroyed in a car crash.
The movie is in theaters on Nov. 4.