The film stars are down under shooting scenes for Waititi's Thor: Love and Thunder film, as is Russell Crowe, who was seen on a bike ride with Ora last week.
One fan reported seeing the couple kissing inside a restaurant, while some questioned whether Ora would play a role in the film.
Another wrote on Twitter, "You being a Thor or nah @ritaora?"
"Idris Elba is on Rita Ora's Instagram (I make no apologies, I love her problematic a**) so does that mean he's in the next Thor?" another asked.
The Daily Mail has reached out to representatives for Ora and Waititi for comment.
Kiwi Oscar-winning director and actor Taika Waititi and Academy Award-nominated producer Chelsea Winstanley are reportedly separated.
The pair, both 44, met over two decades ago when she interviewed him for a documentary about Māori artists, and then reconnected in 2010 while working on Boy.
They married nearly two years later in New York and share two daughters Te Hinekahu, 7, and Matewa Kiritapu, 4.
But according to a report by pop culture website Page Six, the pair quietly separated two years ago.
Rita Ora is currently down under filming the upcoming series of The Voice Australia.
