Quentin Tarantino's Once Upon a Time... in Hollywood script was locked in a safe during filming.
To keep details of the movie — which was nominated for 10 Oscars, taking home two, Best Supporting Actor for Brad Pitt and Best Production Design — a secret, "We kept the third act in a safe in the accounting department," says William Paul Clark, Tarantino's first assistant director, in Filmmaker magazine.
"You come, you get your script, you go into the little room, you go read the third act ... When you're done, you give the script back, they put it back in the safe and you leave."
Meanwhile, Tarantino previously admitted he's coming to the "end" of his movie-making career.
The director has claimed he'll walk away from the business after his next film, as he looks towards the next chapter of his life.
Tarantino said: "I answer the question and I get blamed for talking about it too much, when I'm not the one bringing it up.
"I don't have a super-great answer. I guess the idea is nothing lasts forever. I've been making movies one way for a while. I've built my whole life to do that. I didn't get married, I didn't have children.
"I kind of just set up that this is my time to make movies. I'm very lucky I've been able to work at a high level of opportunity that most filmmakers, at least in Hollywood, do not have the luxury of working, and I've appreciated it."— BANG
Once Upon a Time...in Hollywood is now streaming on Netflix.