Robert De Niro comes clean on whether his 'Taxi Driver' monologue was ad-libbed

Robert De Niro was remarkably chill during his virtual appearance on Monday's edition of The Tonight Show Starring Jimmy Fallon, and that's to be expected from a two-time Oscar-winning icon who has seen and done it all.

Fallon joked about De Niro's demeanor ("I can tell you're excited as much as I am"), but he got the 77-year-old to open up a little by offering up myths that have surrounded his illustrious career for De Niro to either conform or dispel.

Is it true that De Niro originally auditioned as Sonny Corleone for The Godfather before he landed his Oscar-winning role of Vito Corleone in The Godfather: Part II? Yes, and Fallon played a clip from that audition.

Was De Niro really originally cast as Josh, eventually played by Tom Hanks, in 1988's Big? Also yes.

And could it possibly be true that De Niro's iconic line ("You talkin' to me?") from 1976 crime drama Taxi Driver was not actually written in the script? "More or less, yeah," the legendary New Yorker affirmed.

De Niro additionally discussed this year's Tribeca Film Festival, beginning tomorrow (June 9), which he co-founded in 2002. Watch the full Tonight Show segment below.