A Google Maps Help thread have reports that are confirmed from Google, that Google had a bug that indeed knocked parts of Google Maps New Zealand off the map.

Google’s Mike CH confirmed the issue saying:

We messed up – very, very sorry about that. It’s fixed now and we’re busy drawing up a list of things we can do to ensure it doesn’t happen again. Once again, apologies for the inconvenience.

He did not say exactly what went wrong, but the issue seemed to be somewhat manual, being that they want to make some policies to prevent it from happening in the future.

The map details for New Zealand were not available, but the satellite images were. Now everything seems to be working now.

Forum discussion at Google Maps Help.