You can see the same error in The Avengers: F-35B hovering and firing guns from the intakes. I think it's a bad job of converting from a AV-8, which does have

You can see the same error in The Avengers: F-35B hovering and firing guns from the intakes. I think it's a bad job of converting from a AV-8, which does have internal guns, located under each intake.