13. Gaga helped Cooper get a feel for what a real-life concert is like backstage — Gaga was even candid about how drugs are readily available once you become famous.
14. While filming, Gaga and Cooper developed a shorthand. When Cooper wanted Gaga to evoke a feeling of warmth and love he would whisper “Tony” — a nod to Gaga’s close relationship with Tony Bennett.
15. In order to give the film a feeling of authenticity, Cooper casted Gaga’s actual dancers, choreographer, and hair and makeup artists.
16. Lukas Nelson, Willie Nelson’s son, helped co-write a majority of the songs — Cooper approached him about the project after seeing him play guitar at a Neil Young concert.
17. Nelson and his band, Promise of the Real, appear as Jackson and Ally’s band in the film as well.