Before the prison riot the cons are using mirrors to look outside of their cells. When one of them looks at the clock through the mirror, the image is not reversed as it should be.
Romanian documents shown are written in Cyrillic letters, but Romanian is a Latin-derived language which has always used the Latin alphabet.
Protagonists rely on full moon setting at midnight on the Sea of Galilee to determine location of birth of the anti-Christ. Full moons are always at zenith - directly overhead - at midnight local time. Only half-moons (waxing half moons at that) set at midnight local time.
When Josepha phones London, we can see the National Gallery Museum in Trafalgar Sq., but in the screen it is said British Museum.
The last book in the New Testament depicting the Apocalypse is called Revelation not Revelations, a fact which several characters in the series get wrong.