There are several popular answers to this question from fans and critics. This is an attempt at cataloging them, incorporating previous answers to this FAQ, the IMDb boards, and reviews or critical essays:1) Sam sees Riggan flying away because he a) always had powers or b) has suddenly developed or actualized them. He flies away as a (magical or symbolic) triumph of some sort (art, celebrity, self-integration, or redemption).2) Sam thinks she sees him flying away because of a) a schizophrenic break or b) drug-induced hallucination or c) shock. Actually, Riggan is dead on the ground.3) Sam stoically reacts to her father dead on the ground and looks up, realizing that he will have long-lasting celebrity and/or is finally free from his torment.4) Sam doesn't know where her father went, but sees the meteor-like object in the sky, which fills her with awe.5) The whole hospital scene is Riggan's dying thoughts or afterlife fantasy, which begins when he shoots himself on stage. Riggan imagines what he would want to happen.6) The whole movie is Riggan's dream, or dying thoughts from when he killed himself on the beach, or afterlife fantasy. Riggan imagines what he would want to happen.7) We are made to imagine what Sam sees. This, like other ambiguous parts of the movie, creates an open-ended interpretation game, and makes the viewer part of the delusion and/or artful solution.8) We are made to imagine what Sam sees, and then to question what we have imagined:-First we imagine her seeing him flying, as a triumph of some sort (art, celebrity, self-integration, or redemption)-Second we realize that this is impossible because Riggan's powers have been established as hallucinations; the movie ends with an unreal yet hopeful solution (whether artful, or lying, or winking) to a real and sad problem (in short: a mentally ill Riggan committing suicide to go out 'on top', when really he has "confused being admired with being loved" as his ex-girlfriend says).
-and after he stop flying and go to the play when he entering the theater the taxi asked for his money .that established as hallucinations.
"The Unexpected Virtue of Ignorance" is the title that the critic Tabitha gives to her review of the opening night of Riggan's play. Tabitha believes that Riggan is ignorant of the art of the theater. In her review, she considers the unexpected virtue of his ignorance to be his successful performance revitalizing American theater, including the gunshot and blood: "Thompson has unwittingly given birth to a new form, which can only be described as super-realism....The blood that has been sorely missing from the veins of American theater." The meaning of this as a secondary title for the movie itself, or even Tabitha's deeper meaning in choosing the title for her review, is beyond the scope of a FAQ, but it could be variously optimistic or pessimistic, in keeping with a movie that is quite open to interpretation. Lastly, the secondary title is potentially an in-joke, stemming from the director and writers' claims that the movie is rife with all of the artists making fun of themselves, and that the director and writers hadn't made anything this comedic before.