1) There are numerous delusions stemming from gross ignorance among most believers of basic, fundamental facts about Babi and Baha'i history (not trivial details and minutia). I am thinking here specifically about the Babi uprisings and the reasons for Bahaullah's arrest, exile, and later house arrest.
2) The failed prophecies, like the ones stating that the Great Peace would come by the turn of the last millennium, when it did not.
3) The use of Pilgrims Notes when it suits the needs of the present narrative, but their facile dismissal if they do not fit the current narrative.
4) The references by Shoghi Effendi to pending apocalyptic wars, societal demise, and decay. These processes are later referred to by the Universal House of Justice as "disintegration" and other euphemisms.
5) The process of entry by troops.
6) The chapter titled Administrative Order in World Order of Bahá'u'lláh.
7) Basic historical inaccuracies, like 'Abdu’l-Bahá's statement in 1912 that "the first proclamation of liberty, of freedom from slavery, was accomplished in this continent" which is factually incorrect. In the same speech he says "This effort on the part of the white people in America should never be lost sight of, and therefore you must be grateful to the whites, for they were liberators of your people not only in this country, in the continent of America, but elsewhere, in Africa." Or the numerous historical inaccuracies mentioned by Shoghi Effendi, like the ones he mentioned in The Unfolding of World Civilization.
Source : https://www.reddit.com