These were included with some releases of the Toa Iruini and Norik sets to correct an error (however, it would appear the correction ended up even more erroneous instead).
So, the topic now is - Are there more of these kinds of corrections out there? Have you seen any? If so, pictures of them would be great as well!
There definately exist more for example the manas or the technic droideka.
The fire station from lego city released in 2005 had one too.
Also the 05 playset might have had some too.
This piece is the part that holds the tail of the ship in place, and because of the piece used, the tail had a tendency to fall off. As a result, this sheet was made which uses slightly different pieces to make the construction sturdier.
I dont have a picture, but the blacktron message intercept base has a black and white correction sheet. I think one or two of the Technic star wars figures do too