Iñárritu originally conceived the film as a comedy filmed in a single shot set in a theatre. The original choice behind the film's genre, which was subsequently re-adapted to concentrate on Riggan's final emotional tail spin, came from the director wanting to see a change in his approach. All his previous films were dramas, and after directing Biutiful (2010), he did not want to approach his new film in the same tragic manner again. The decision to make the film appear as a single shot came from his realization that "we live our lives with no editing." By presenting the film as a continuous shot he could "submerge the protagonist in an 'inescapable reality' and take the audience with him". Iñárritu shared his idea with Argentine screenwriters/cousins Nicolás Giacobone and Armando Bo, as well as playwright Alexander Dinelaris, Jr., who had all worked with him on his previous film. Their first reaction was to tell him the continuous-shot idea could not work. According to Iñárritu, he had dinner with director Mike Nichols in New York two weeks before he began shooting the movie. Iñárritu told Nichols of his plan for how he was going to shoot the movie as one long take. Nichols predicted it would be a disaster because not having the ability to use cuts in editing would inhibit the opportunities for comedy. Iñárritu said the meeting didn't deter him, but was instead helpful in raising his awareness level of the difficulty of what he was about to do. Iñárritu cast several of the leading roles before the film was financed. Among these was the lead role. Early in script development, Iñárritu did not have Keaton in mind, but he had changed his mind by the end: "When I finished the script, I knew that Michael was not the choice or option, he was the guy". Iñárritu cast Keaton for his depth in a variety of acting styles: he could handle the demands of the stage, up-close work, and comedy and empathy "with a profound depth to both." Keaton knew about Birdman before Iñárritu contacted him. He was in the middle of production of another project when he learned that Iñárritu was making another film. Keaton, a fan of his work, flew home to find out more. Iñárritu sent him the script and they discussed it over dinner. The first thing Keaton asked the director was whether he was making fun of him (regarding his role in Tim Burton's Batman films), but after Iñárritu explained the role, its technicalities and the film's production, Keaton agreed to play Riggan. Before shooting began, Iñárritu sent his cast a photo of Philippe Petit walking on the tightrope between the Twin Towers. He told them, "Guys, this is the movie we are doing. If we fall, we fail." Filming began in New York City during the spring of 2013 with a budget of $16.5 million. It was shot in two months, including rehearsals. It was largely shot inside Broadway's St. James Theatre. Keaton and the rest of the cast had to adapt to Iñárritu's rigorous shooting style, which required them to perform up to fifteen pages of dialogue at a time while hitting precisely choreographed marks. Given the unusual style of filming long takes, Edward Norton and Michael Keaton kept a running tally of flubs made by the actors. 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. Because the movie was carefully rehearsed and shot in sequence, the editing process only took two weeks.
The film stars Michael Keaton with a supporting cast of Zach Galifianakis, Edward Norton, Andrea Riseborough, Amy Ryan, Emma Stone and Naomi Watts. The cast gave, probably, the best performances of their careers. Especially to Keaton, who is back. Whether intentional or not, Keaton was the only one who could have played the role of Riggan Thomson. And he fit the part perfectly. This is first leading role since The Merry Gentleman (2008), which he also directed. 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 of any he has ever played. And boy did he pull off a show. Definitely awards worthy!
Simon says Birdman or (The Unexpected Virtue of Ignorance) receives: