"I liked the approach, which was not to make a big thing out of it, which is where I hope we are going as a species, to not politicise one's personal orientations," said Cho.
Celebrating its 50th year, the Star Trek franchise has long broken new ground on film and TV, and in 1968 famously featured the first interracial kiss ever screened on US TV.
Takei, who has gone on to become a prominent activist for LGBTIQ rights, dared not reveal his sexuality at the time for fear of ruining his career in a much more closed-minded time.
"If I wanted to work as an actor I had to keep it a secret," Takei told News Corp last year.
"Back then I couldn't marry a white person - that was against the law here, miscegenation. But now I am married to a white dude so we have changed."
Emotions were still raw at the death of cast mate Anton Yelchin, who played Chekhov in all three Star Trek movies and was tragically killed last month when he was accidentally crushed by his own car.
The cast members, who were returning to Sydney seven years after the first movie had its world premiere at the Opera House, said it was a much more sobering visit this time - and that the new film, which opens on July 21, would be a tribute to the talented young actor.
"It's bittersweet with the passing of Anton," said Kiwi Urban, who will soon start production on Thor: Ragnarok on the Gold Coast.
"It's devastating losing someone in your family - this feels like it should be a time for celebration not just of the film but of him, his extraordinary talent and the beautiful man he was.
"I'm having a difficult time coming to grips with talking about him in the past tense - it's very raw and very painful."
