Actually, the original surveys done in the 1840s were all screwed up. Some of the township lines are off by 100s of feet. But I guess when you're in the wilderness eating mosquitoes and getting chased up trees by wolf packs, you tend to hurry the job a bit.
For example, dozens of miles of Wisconsin actually belong to Michigan. Again it's a mess-up by the original surveyors. It would be interesting to see Michigan challenge the ownership. We were going to form up an expeditionary force and take it back, but we couldn't get enough beer for the multi-year squatting action it might take. :-)
In my case, the county bought my neighbors land to widen a road. What they didn't take into account is that a small piece of my land abutting the neighbor's was also taken. By taken I mean that vehicles use it. It's part of a turnaround at a deadend dirt road. We have some strange shaped land around here due to mining back in the 19th century. I'll need to send a legal notice to them so the land isn't taken by adverse condemnation.
Although I am not an attorney, there is a statute of limitations of 5 years in California. It would appear that, even if the city did not have a legal right, the city had open and notorious use of the road and has created an easement through a prescriptive right. It could always "take" the land for public use through eminent domain and I imagine, compensation would be waived because of the statute of limitations on any claim.