The music heard in the film (Souvenir de Los Angeles, Op. 11, written by Emile Sauret) was actually played inside Barclay Hotel when it was at its prime by Dion Romandy and his orchestra. The recording in the film is new and performed by Michi Wiancko (violin) and Dina Vainshtein (piano).
The saxophone heard over the end credits was played by a street musician in downtown LA and was recorded live on location by the film's producer Diana Ward.
This is the first film that Nawaf Al Janahi has shot on an iPhone.
Everything you see in the film was shot from outside the building of the hotel. The shots of the cafe were either through its windows, or reflected off them.