So I'm looking at the map, and these turret ranges start to look familiar. So I go way up to my walls at my original base, and what do you know, they match up exactly to these false turret range images I'm getting on my map where I am expanding way down south. Whats more is the turrets I'm building to fight biters on my new expansion now show their ranges up at my original base. I would guess am 10,000 or more tiles south of the spawn. I am not playing with any mods.
These are pictures of the map with turret range turned on. You can clearly see where the real turrets are showing their range and where there is ghostly turret range with no source.
At the wall in my original base
At the expansion at the south of the map where I am building a railroad
This bug was found in 0.15.18. I can test in the latest version and provide a save and instructions to recreate if needed.