Unused stock footage from the episode, Assignment: Earth. This and other footage used in the episode was obtained from NASA, which shoots much of its footage in the anamorphic format.
From this footage an optical printer is used to create a duplicate print of the desired area.
More unused NASA stock footage
Cut scenes from Spock's Brain.
After discovering Spock in sickbay, Scott uses McCoy's computer to find a means of making Spock ambulatory.
A shocked crew looks up to find Spock on the bridge.
Unused shot from Charlie X.
These two bridge set walls usually straddle the main viewing screen. This shot has more open space where the Thasian would be superimposed. The cleaner looking background was most likely an insurance shot if the scene which was eventually used appeared too cluttered.
Thanks to Joe L. and David T. for the Assignment: Earth clips.
Thanks to Audrey A. for the Spock's Brain clips.
Thanks to Joseph A. for the Charlie X clip.