Wikidata is the source I used to get metadata about Wikipedia articles. Sometimes the data is automatically extracted from Wikipedia articles which introduces these errors. What's nice is that the timeline representation easily shows these outliers and will help us fix them !
+1, I noticed and fixed a few erroneous dates that would have presumably been difficult to surface otherwise
The problem is that there's no guarantee that extraction errors will always end up as outliers. Instead, outliers are merely the errors that are easiest to find.
<Insert bullet-ridden bomber image here>