Here is what I picked up here and here.
Brown claims: Copernicus was murdered by the Catholic Church.
Fact: Copernicus died quietly in bed at age 70 from a stroke, and his research was supported by Church officials; he even dedicated his masterwork to the Pope.
Brown claims: “Antimatter is the ultimate energy source. It releases energy with 100% efficiency.”
Fact: CERN, the lab which plays an important role in his story, actually debunked this claim on their website: “The inefficiency of antimatter production is enormous: you get only a tenth of a billion of the invested energy back.”
Brown claims: Churchill was a “staunch Catholic.”
Fact: Any history buff could tell you that Churchill wasn’t Catholic, he was Anglican; nor was he particularly religious. The only things Churchill was staunch about were cigars, whiskey, and defending the British Empire.
Brown claims: Pope Urban VII banished Bernini’s famous statue The Ecstasy of St. Teresa “to some obscure chapel across town” because it was too racy for the Vatican.
Fact: The statue was actually commissioned by Cardinal Cornaro specifically for the Cornaro Chapel (Brown’s “obscure chapel”). Moreover, the sculpture was completed in 1652 — eight years after Urban’s death.
Brown claims: Bernini and famed scientist Galileo were members of the Illuminati.
Fact: The Illuminati was founded in Bavaria in 1776. Bernini died in 1680, while Galileo died in 1642 — more than a century before the Illuminati were first formed.
I am not a hard sell. If you want to put in your book that Atlantis was a superhightech civilization destroyed by the extra-dimensional Eddorians in order to thwart Arisian attempts to breed mankind to create the Kwisatz Haderach, child of the Lens and the father of the race that will rule the Sevagram, I will suspend my disbelief like it was bouyant with helium.
You want to establish that a race of robots hidden in a secret base in Mount Ararat has been guiding human history since the time of Enoch, I am your man.
You want to say the Freemasons (who built the temple of Solomon) are the archenemies of the Slavemasons (who build the Great Pyramid of Cheops) have been fighting a duel to place or remove feng-shui-significant stonehenge, monuments, and Cathedrals at goethermal accupuncture points across Europe, Asia and the New World since the Bronze Age, and that all major wars and architectural firms are under their control, and involved in a secret aeons-old Cold War to prevent the telluric current from destroying this world as unwise abuses of the geomancy of the canals of Mars did that remote, dying world? Sure!
Shiwan Khan is actually a time-travelling alien from planet Mongo, granted eternal youth by the powers of alchemy, and he long ago replaced the royal family of England with Life-Model-Decoys which he controls with the ten magic rings he found in the wreckage of a spaceship from planet Maklu IV? Why not?
Lord Byron was a vampire? You would have to pay me money not to believe that.
Queen Elizabeth ran of coven of witches whose stormcrafty drowned the Aramda of Philip of Spain, after he had secretly adopted the practice of mass human sacrifice from his wife who was secretly an Aztec princess in order to gain magical control of an entire hemisphere's worth of demon-cursed Mexican gold? Not only possible, but likely!
The entire Middle Ages is an elaborate fraud perpetrated by the Roman Empire, which never fell but simply went into hiding once Virgil the Magician discovered the tunnels leading to Pellucidar in the Hollow Earth? Seems reasonable to me!!
The US Congress killed and replaced by shape-changing seals from the Dreamlands who talk like movie pirates? Brother, I wrote it!
But the Catholic Church MURDERED Copurnicus? Oh, my aching back. He was a churchman himself: why not simply order him to recant his findings?