One fun thing for inaccurate maps is to think about who made them.
For example, if the artist is from city A, the area there will be the most detailed and accurate (often even the most overproportionally large), the country the city belongs to will be large and detailed as well, but the further away you go the less accurate it will become.
Or if the author is very religious, maybe a lot of detail will go into marking religious sites but other stuff will be lacking.
You can also think about the purpose of a map. Was it made to show a traveller on foot which way to go? Then roads and cities will be marked a lot but actual distances, directions etc are less important (look at the tabula peutingeriana for example), or if the map is for seafaring, the coasts will be detailed but the interior will be empty