Probably shoulda mentioned this last patch, but forgot; going to the hanger after getting back to the base (may or may not require going to the lab first, forgot to check before saving) and inspecting the vehicle has you prepared for the mission to go to Hilly Hill, and upon accepting has you walking around the initial map with the saucer version following. No interactables exist on this map, making it a softlock. Amusingly, each of the characters in the menu have different facial expressions.