“Jojo Rabbit” director Taika Waititi says he felt “very nervous” playing the imaginary Hitler in his film about a young boy growing up in Nazi Germany during World War II, and that it was never his intention to do so when he wrote the script for it.

“It wasn’t my intention at all writing the script and it was actually something Fox Searchlight encouraged me to do,” Waititi told TheWrap’s Beatrice Verhoeven at the Toronto International Film Festival. “They encouraged me to play the role and I felt very nervous about that. But then I thought, ‘you know what? Once in a generation, an actor comes along who sort of changes the game…’”

“Well, you couldn’t afford him,” Stephen Merchant, who plays a Gestapo officer in the film, joked.

The film is set in a town in Germany where 10-year-old Jojo Betzler (Roman Griffin Davis) wants nothing more than to be a good little Nazi. But he’s a scared little kid who earned the nickname “Jojo Rabbit” when he refused to kill a rabbit at Nazi training camp. So he creates an imaginary friend: a goofy Adolph Hitler who encourages the boy’s worst impulses. The local Nazis are played by Sam Rockwell, Alfie Allen, Rebel Wilson and Merchant.

When asked what the hardest part about playing Hitler was, Waititi said, “just that he’s so ugly.” Turns out, Waititi shaved his real mustache and used a stick-on one for Hitler’s distinctive facial hair. “I didn’t feel comfortable growing one and walking around town on my days off,” he said.

“The first time I saw Taika in costume, I cried,” Davis said. “He didn’t do anything, I just cried. It was a shocking thing.”

“Is that because of the quality of his performance?” Merchant chimed in. The actor, whose most recent credits include “Fighting With my Family” and “Good Boys,” went on to joke that he hasn’t received the praise for his performance that he had hoped for from Waititi.

“I had a quick skim of the script to see how many lines I had, and I had a good portion of dialogue and I largely dominated the scenes I was in, so I thought, ‘yeah, I’ll do this for no money,’ as a favor,” Merchant said. “I never really felt like I got the gratitude I deserved for shlepping all the way to Prague and dressing up as a Gestapo officer, but maybe that will come down the pipe at some point… Maybe finally I’ll get some compliments from the director.”

“Jojo Rabbit” also stars Scarlett Johansson and will hit theaters on October 18.

Watch the video above.

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Oscar Race Begins: Fall Festivals Bring Moment of Truth for ‘Joker,’ ‘Jojo Rabbit’ and Many More

‘Hitler’ Reacts to Taika Waititi’s ‘Jojo Rabbit’ in Hilarious Take on Old Meme (Video)

Taika Waititi’s Adolf Hitler Gives Motivational Advice in ‘Jojo Rabbit’ Teaser (Video)