Arnold Schwarzenegger’s son Joseph Baena announced he’s working on a new film in an Instagram post shared Monday. Baena, who has been working on his acting career, shared a photo of himself on the set of the upcoming film “Lava.” “Excited to be filming the movie ‘Lava’ with the @bitflixnfts team!” Baena captioned the photo before adding, “Comment what you think is happening in this scene.” Besides working on this project in Hawaii, Baena, Schwarzenegger’s son with Mildred Baena, also wrapped up filming on “Bully High” this year, according to his IMDb. Joseph Baena announced he is working on a new project in Hawaii. (Photo by Paul Archuleta/Getty Images) Acting…