Unfortunately, not much can be done about this. Most phones will report the same Cell ID when a call is in progress. Likewise, some phones will get "stuck" to reporting a single cell id for a certain length of time. Another possibility is that the GPS device is incorrectly reporting the position; and as a result the location may keep changing wildly before it settles down to the right location.
While the app and site try to filter this bad data, there is not much that can be done to fix it. As more data is gathered, these errors will slowly decrease until the map becomes more and more accurate.