General:
* Superficial - focusing on appearances or what is obvious, not going deeper.
* Shallow - not deep or profound; lacking in substance.
* Surface - the outer layer or part of something.
* External - on the outside; relating to the outside of something.
* Exterior - the outer part or surface of something.
More specific:
* Subsurface - just below the surface.
* Peripheral - on the edge or margin; not central.
* Skin-deep - superficial; lacking in depth or substance.
* Tangential - only slightly related to the main point.
* Ephemeral - lasting for a very short time.
* Transient - lasting only for a short time.
The best word will depend on the specific situation and the meaning you want to convey.