Hard Times - S1-E3
Other mistake: Crowley shows acute discomfort while inside the church with Aziraphale and the Nazi spies as he is on consecrated ground. However, (spoiler alert) once the bomb destroys the church he is perfectly comfortable. The key word here is "ground" - it is the land upon which the church stands that is consecrated, not the building itself. (This allows churches to be rebuilt if they are demolished or destroyed.) Crowley should still be in considerable discomfort after the church has been blown up.
Other mistake: When Aziraphale is reading The Book in his shop, you see various written prophecies pass by on screen. These are the original 1990 versions, not those actually read out later in the show. E.g. "When Orient's chariot inverted be, four wheels in the air" vs "When Robyn's chariot inverted be, three wheels in the air" and the inclusion of The Other Four Horsemen of the Apocalypse, who were cut from the show.