Fallon, as he told Scorsese, has done his fair share of De Niro impressions over the years — "In front of him, and behind his back," he cracked — and asked the director if he'd cultivated one after working with the actor for so long.
While Scorsese demurred at first, he said of his relationship with De Niro, "Over the years, we kind of, somehow, melted into each other in a way." The director then noted that De Niro's interaction with Frank Vincent during the "shinebox" scene in Goodfellas has become part of his own repertoire, and proceeded to deliver an on-point, "Well, you did insult him a little bit," followed by a threateningly casual: "Ok!"
Scorsese also stuck around for a round of The Tonight Show's game, "5-Second Summaries," in which the guest and the host have five seconds to describe the plot of a movie without using the title or any actor names. While the director's wealth of film knowledge helped him speedily name The Wizard of Oz and The Revenant, his familiarity with film tropes backfired as he tried to describe Casablanca to Fallon: "Soft-hearted tough guy in love with the hero's wife, and everybody's noble."