Burt Reynolds died after rehearsing lines for his final movie role

The filmmaker told Esquire magazine: "I found out from three different people that the last thing he did just before he died was run lines with his assistant.

"Then he went to the bathroom, and that's when he had his heart attack."

Brad Pitt also appears in the movie and he admitted the two days he shared on set with Burt gave him some of the "greatest moments" in his career.

He said: "I'll tell you one of the greatest moments I've had in these however many years we've been at it in this town: getting to spend two days with Burt Reynolds on this film.

"You've gotta understand, for me, growing up in the Ozarks and watching 'Smokey and the Bandit', you know, he was the guy. Virile. Always had something sharp to say - funny as s**t. A great dresser. Oh, man.

"And I had never met him, so being there with him reminded me of how much I enjoyed him as a kid. And then getting to spend those days with him in rehearsal, I was really touched by him."

Following Bert's death, his niece, Nancy Lee Brown Hess, admitted he had been looking forward to working with Tarantino and fellow actors Brad Pitt, Leonardo DiCaprio, Margot Robbie, Al Pacino and Kurt Russell on the movie.

She said in a statement: "My uncle was looking forward to working with Quentin Tarantino (in 'Once Upon a Time in Hollywood') and the amazing cast that was assembled."

Bruce Dern eventually took over the role of the rancher.