What historical event has he taught that did not happen?
Just recently Glenn spent time on his show touting artifacts in a museum in Ohio as items found in Indian burial mound regions which show a Hebrew influence in ancient pre-history times of this continent. He spouted a vague replay of what Mormonism apologists claim for the items, and in fact represented the finds incorrectly!
In reality the items were most likely stolen from a Jewish person around the 1800 mark--carved during the medieval period either in Spain or France, based upon the stone work, brought to this continent as family heirlooms of a devout Jewish family-- and once stolen, thrown away into the detritus trench near one of the much picked over Indian Mounds in the Ohio region of Indian mound earthworks. Several items were found and not all in the same location but in the same general vicinity to the Indian mounds.
The skull of the Jewish person was discovered with the forehead phylactery still attached, and the remains were deemed recent--bured within thirty years of discover--based upon the condition of the remains and the lack of natural effects which would occur if the skeletal remains were two thousand years old. There was also forensic evidence regarding the lettering system.
You can read about the controversy regarding these artifacts by googling 'The Newark Stones': look for the definitive explanation by Rachel Altman [ http://www.bibleinterp.com/articles/Altman_Newark.shtml ]
Dr. Altman's penetrating comment is: "If you found a US penny in a trench at a dig that was assumed to contain only ancient items, you wouldn't claim the penny to be a forgery when you saw it. First, however, you would have to recognize that it's a penny."
Sadly, Glenn was in gross error and omitted facts he had to have had regarding Phoenician contacts with this continent as the likely source of the stede and the mathematics of SOME mound arrangements. Whether Glenn was mislead and touted these errors innocently, or was touting these assertions because he wanted them to be true, he was in gross error and send the errors out over the airwaves. Personally, I believe he was mislead by ardent staff wishing to reinforce their Mormon beliefs. There is an LDS instructional video at Youtube which promtoes the exact same false assertions that Glenn recited to viewers.