Joker star Joaquin Phoenix often worried co-stars by walking off set in the middle of a scene

Joaquin Phoenix would walk off the set of Joker while in the middle of filming a scene if he “wasn’t feeling it”.

The actor plays Arthur Fleck in the new film, which is generating serious Oscar buzz following its Venice Film Festival premiere, and director Todd Phillips has offered a glimpse into what life was like behind-the-scenes.

In an interview with The New York Times, Phillips revealed that Phoenix often worried his co-stars by leaving the set during a take.

“In the middle of the scene, he’ll just walk away and walk out,” Phillips said. “And the poor other actor thinks it’s them and it was never them — it was always him, and he just wasn’t feeling it.”

Phoenix’s co-stars include Zazie Beetz, Marc Maron and Brett Cullen. Robert De Niro also stars in the film, but the piece points out that Phoenix never acted this way in front of him.

It’s unclear why his fellow actors felt responsible for his walkouts.

Phoenix is expected to earn a Best Actor nomination for his role as Arthur Fleck in the film that received an eight-minute standing ovation following its premiere at Venice Film Festival.

The actor also attended Toronto International Film Festival (TIFF) where he delivered an emotional speech crediting his late brother River for his successful career.

Joker is released in cinemas on 4 October.