The Error Page is a page that appears when an error has occurred, like a deleted page, user or non-existing page on the website.
The old design from 2007-2012 showed an orange-shirted noob "walking" a pack of dynamite with a clock attached to it.
The next one shows a white isosceles triangle with yellow outer lines with an exclamation point inside it. Existed from 2012-early 2014
The newest design used from 2014-present now shows Builderman falling into a hole.