Because the movie was carefully rehearsed and shot in sequence, editing took only two weeks.
There are only sixteen visible cuts in the entire film.
Given the unusual style of filming long takes, Edward Norton and Michael Keaton kept a running tally of flubs made by the actors and actresses. Emma Stone made the most mistakes. Zach Galifianakis made the fewest. He actually did mess up a few lines during the filming, but played his mistakes off well enough that the shots were included in the film.
The movie was largely shot inside Broadway's St. James Theatre. Michael Keaton and the rest of the cast had to adapt to Alejandro G. Iñárritu's rigorous shooting style, which required them to perform up to fifteen pages of dialogue at a time while hitting precisely choreographed marks.
Michael Keaton said this movie was the most challenging he has ever done. He also said that the personality of his character Riggan is the most dissimilar to himself or any he has ever played.
Alejandro G. Iñárritu: [Mexico] Iñárritu includes paraphernalia from his native land at several points. When Riggan enters the liquor store, the walls are covered in Christmas lights, which are in the form of Mexican chili peppers. When Riggan is walking in his underwear on Broadway, the sound of the famous tamales Oaxaqueños that are sold in Mexico can be heard. In the final sequence, the sound of the car that sells camotes is also clearly heard.