Egyptians are famous for their populist and flawed interpretation of Dendera Light Bulbs - the claim used to say that the pharaohs had invented light bulbs. Such flawed claims have a history of their own.
Where do I find flawed historical claims used to support nationalism, in various countries across the world. For example, what are the flawed histories propped up by Mexicans or the Inuits or the Vietnamese to prop up their own corresponding historical exceptionalisms. For example, Indians sometimes subscribe to false history that several of the mosques were reconverted temples.
tl;dr: Global Inventory of false historical claims used to prop up nationalistic fervour, or ethnic superiority.
I'd also be interested to know if there is a collected history of these claims. Seems like leaders with large cults of personality would be ripe for these sorts of claims. In the Middle East, these sometimes came in things like neo-Pharaonism, neo-Phoenicianism, neo-Babylonianism.
I can tell you about 2 that might fit your criteria in Saddam Hussein's Iraq. Saddam invested tons of resources into archaeology in an attempt to connect his rule with the ancient Mesopotamian culture and leadership - and so began a reconstruction of Babylon. Bricks that were replaced during this reconstruction were inscribed that it was "done during the era of the leader, Saddam Hussein." He further connected himself with Nebuchadnezzar on the first anniversary of the Iran-Iraq war with the slogan "Yesterday Nebuchadnezzar, Today, Saddam Hussein" - explicitly making a parallel between the Iran-Iraq war and Babylonian-Persians wars of the past.
The second is the creation of the Victory Arch in Iraq. The arch features two massive arms opposite each other, bursting through the earth, each wielding a sword. At the base of each arm is a net filled with actual helmets of fallen Iranian soldiers. Kanan Makiya notes that the arms were modeled after Saddam's own arms - a casting of his arms was blown up to gigantic proportions and shipped overland from Germany to Iraq. The sword these arms are grasping is very iconic - the sword known as dhu al-faqar was purported to have belonged to Muhammad, and to have held magical properties. Makiya claims the design of the sword would be recognizable in an Islamic context. So Saddam's statue, modeled on his hands, is grasping the sword of the prophet (and thereafter 'Ali), signaling himself as heir, strangely enough, to even Shi'i Islam.
I know neither of these is a global inventory, but perhaps they are interesting points as you continue your search. Check out
Abdi, Kamyar. “From Pan-Arabism to Saddam Hussein's Cult of Personality: Ancient Mesopotamia and Iraqi National Ideology.” Journal of Social Archaeology 8, No. 1 (2008)
and
Makiya, Kanan. The Monument: Art and Vulgarity in Saddam's Iraq. London, I.B. Tauris. 2004.
for more on what I mentioned above.
Check out Eric Hobsbawm's anthology The Invention of Tradition which focuses on the invention of a mythical past to suit contemporary politics.
Although it's not quite what you're asking for here, it's worth checking out James Scott's Seeing like a State: How Certain Schemes to Improve the Human Condition Have Failed in that it provides a global perspective on the flawed justifications states used to justify their projects.
