Originally, Wen was supposed to have a role at the beginning of the film in the matchmaker scene as the potential mother-in-law but the part required her to be in Auckland, where they shot most of Mulan, for a month.
But Wen is a regular on Marvel TV series Agents of SHIELD, also produced by Disney.
"The producers of Agents of SHIELD just threw up their hands, 'We can't lose you for a month!'. I totally understood, and I'm always very Zen about this stuff," Wen told The New York Times. "I said, 'Look, if it was meant to be, it was meant to be. We all tried, and it's too bad.'
"We sort of let it go and then (producer) Jason (Reed) and (director) Niki (Caro) came up with this great idea where instead of shooting an entire scene, I'd just make a cameo at the very end to announce Mulan to the emperor.
"I thought that was very appropriate and just wonderful, a little Easter egg where I could pass the baton. And this time, they only needed me there for a week. So it all worked out!"
Wen, who has starred in films including the Joy Luck Club and Prom Night, recently voiced Mulan again in Ralph Breaks the Internet. It was in a scene with a bunch of Disney princesses whose characters were voiced by the women who originated the characters, including Idina Menzel as Elsa, Kelly Macdonald as Merida, Mandy Moore as Rapunzel and Auli'I Cravalho as Moana.
She also recently appeared in an episode of The Mandalorian while Agents of SHIELD wrapped up in May after seven seasons.
The new version of Mulan was originally scheduled to be released in cinemas in late March but had its plans disrupted by coronavirus shutdowns. Attempts to reschedule it eventually led to its streaming release in markets where Disney+ is available.
The film costs an extra $34.99 to access, and is not included in the cost of a Disney+ subscription. From December 4, Mulan will be available for all subscribers.
The live action version has been embroiled in two controversies, including one that sparked a boycott movement after lead actor Liu voiced her support for Hong Kong police during violent confrontations with democracy protesters.
Since the film's release, activists have pointed to the film's credits where producers thanked Chinese government organisations in the Xinjiang province where Mulan was partly filmed.
The Xinjiang province is where a million Chinese ethnic minority Uighur people have been detained and placed in "re-education" centres.
