The model originally (for The Cage) had many features painted in place so that the camera could move just past the center line of the model from the front or back and imply that the model was symmetric. This ability was significantly limited once lighting was added for WNMHGB, but many of these painted aspects of the model fooled audiences and fans into believing that real physical features were present where none existed.
In the image below I've highlighted areas that were painted on rather than being actual physical features (like on the other side of the model)...
... and many people still believe that those aspects were actually there originally, which shows just how well the painted features worked on screen.
In the image below I've highlighted areas that were painted on rather than being actual physical features (like on the other side of the model)...

... and many people still believe that those aspects were actually there originally, which shows just how well the painted features worked on screen.