You talking to me In what movie did Robert De Niro adapt a scene from Shane and improvise Travis Bickle threatening himself in mirror?

The movie you're thinking of is Taxi Driver (1976).

Here's the breakdown:

* Shane Adaptation: The scene where Travis Bickle talks to himself in the mirror is inspired by a scene in the 1953 Western film "Shane," where the titular character speaks to a young boy about the consequences of violence.

* Improvisation: De Niro actually improvised much of the monologue in the mirror, which is a testament to his incredible talent and understanding of the character. The director, Martin Scorsese, encouraged De Niro to explore Travis's inner turmoil and allowed him creative freedom, resulting in one of cinema's most iconic and powerful scenes.