Hailing from the US and UK, Amy Ryan and Andrea Riseborough play Riggan's (Michael Keaton) ex-wife and lover, respectively. Both actresses have had success across film and stage, the former breaking through in movies with an Oscar-nominated performance in Gone Baby Gone. Riseborough, meanwhile, has demonstrated a chameleon-like ability to disappear inside characters as diverse as the young Margaret Thatcher, Wallis Simpson, and an Irish bomber. Together, they discuss the anxieties of theatre life, and the precise choreography of Birdman.

Did anyone mess up the long takes?

Amy Ryan: I fucked up. We got towards the end of the scene and I walked into the camera. We were so close, almost had it, and I crashed into it. And then the second take it happened to the boom operator.

Did you have any room to improvise?

Andrea Riseborough: Everything was choreographed meticulously. There was no actual verbal improvisation but the improvisation lay in the cinematic element of the film, the intimacy, where you can say one sentence in so many different ways and it can mean so many different things. I felt very free that way with Alejandro.

The people working on Riggan's play are in a kind of bubble. Is that what doing a play feels like?

Amy Ryan: That is very much how theatre can be, especially when you get to the technical rehearsal. You can be there for like 14 hours a day, in the dark your whole day. Doing plays in New York, it's always amazing to me going outside to see that there is another city out there. You think, 'Why are they doing these other things? Why don't they care about this very important piece of work we're about to do?' So it can feel like a very tight-knit family, if you're lucky. And a very dysfunctional family, also if you're lucky.

There's a lot of neuroses sloshing about in the film. Is that accurate?

Amy Ryan: Sure. But it changes with the moon and the tides and the audience. A matinee crowd of ladies crunching their candies can bring out a very different performance. I always think Thursday night performances are the best, because it's pay-day and people feel confident.

Andrea Riseborough: Wednesday matinees, I always get really angry. If there's school kids, a lot them don't want to be there. They're all like, 'Fuckin' Shakespeare.' They're just glad they got out of maths.

Edward Norton, Michael Keaton and Emma Stone have all appeared in comic book movies. Would you like to do that?

Amy Ryan: I don't know if it's an aspiration. I don't know if you can ever really get into a character, you know? But as a film nerd it might be fun to go and visit the sets and be a part of it at some point.

Andrea Riseborough: Out of the studio films that I have done, I had a great time doing Oblivion because we worked – Joe (Kosinski, the director) and Tom (Cruise) and I – on that relationship between Tom's character and mine for three months before we even started to shoot. Regardless of whether it was in the future, and we were miles above the planet's surface in the middle of an apocalypse, we wanted them to be a real couple and for that resonate. In the same way in Birdman, Michael Keaton's character's neurosis resonates with every human being. It's the endless embarrassment of being human.

There is a line in the film about Hollywood perpetrating cultural genocide with big action films. What is your take on that?

Amy Ryan: This is a Hollywood film and it is not creating cultural genocide. It's just such a large umbrella to say Hollywood.

Andrea Riseborough: And those films give lots of things to many people as well. They give escapism and hope, and there are sensational Hollywood movies that you watch to be swept away or uplifted by when you really need them. There are so many lovely movies and without sounding too depressing, we all have blood on our hands. We are all part of it in one way or another. Being in it, writing about it, not being in it, watching it, we're all part of the process in some way, I think.

There's another line in the film about celebrity being confused with love. What is your take on celebrity?

Andrea Riseborough: You know, you really just start off thinking about the work and then the other stuff that comes after that, you're so unprepared for. I was very confused when I came out to talk to people when I started doing films. You don't really have that experience in theatre. And then with film, suddenly people are asking what you're wearing. That was a very difficult thing for me. I'd be angry and, like, 'Let's talk about this wonderful piece of work that we've all done.' I realise now to be gracious, because some people are interested in that.

Birdman is out in cinemas on January 1