Yup, default planesets are integrated into the map file, so if the map maker forgets to disable them a staff member has to go in and correct it. They usually discover it after someone posts in the Bugs forum about it.
Originally the RV8 was a test platform for the physics engine since HiTech flies an RV8. He could compare the real performance with the game's. It was later modified with twin 30mm gatlings as an Evil Con Mishun. Later the original model was unlocked at player's request.