He went on to reveal that it's a common occurrence for those starring alongside the 180cm Kidman, who is well known as one of Hollywood's tallest actresses
He said actors either stand on an elevated platform or the crew dig a hole for Kidman to stand in, to even out the height difference.
Morrison and Kidman play the parents of Aquaman, played by Game of Thrones' Jason Momoa in DC Comics' upcoming blockbuster.
This follows Morrison's other roles in major films like Star Wars, Moana and another DC hero flick Green Lantern.
Aquaman also features Amber Heard, Willem Dafoe, Patrick Wilson and Yahya Abdul-Mateen II.
The film is due for release in December.