Hi DoyleChris98 again, sorry the above did not help, I have two more ideas for you that might work.
Have you tried using a feature called the (hole punch), it places a hole where the land is, and once the hole has been placed, then delete the hole using the (X) in the buildings tab, this might get rid of the arrows, as it removes everything that is where the hole is, try and add the holes where the tracks where, then delete the holes and see if the arrows have disappeared.
The last idea is also the last resort, you could delete the effected baseboard with the arrows on, this will delete the baseboard, the ground and most items on it (possibly including the arrows), then replace the baseboard, and check the arrows are gone and rebuild your land what was effected, once you have deleted the baseboard, DO NOT SAVE, in case it did not work, then add a new baseboard in the space left, hopefully the arrows will have gone, but unfortunatly you will have lost one baseboard of scenery, which will need to be redone, but I would sooner delete one baseboard and rebuild it, than delete a whole route and start from scratch.
Hope the above helps, and let us know how you get on.
Joe Airtime