Father Kovak writes down '666' on a sheet of paper to illustrate how it is '999' when upturned. In the next shot it is quite clearly a different piece of paper with a different '666' on it.
Christine runs barefoot in subway tunnels and other underground places so one would expect her feet to become dirty. Yet a moment later in the church, her feet are perfectly clean.
When Jericho is escorting Satan's limo in the car caravan the lead car changes from a Chevy to a GMC. You can see this as it pulls in around 16:30. Also the traffic completely changes e.g. from pulling in front of a bus to a taxi.
After the priests have tried to kill Christine at her home, Jericho is seen walking behind her. In one shot the white door behind her is open but when the frame changes to Jericho the door is shut. In the following shot the door is open.
When Jericho follows the priest through the door in Saint John's church, there is a stairwell behind it turning to the left, leading into the basement. Yet moments before, when we see the door from the other side, it leads into a room on the right. Also, in these two shots, the door opens to different sides.
When "The Man" killed the subway motorman, the train should have immediately come to a halt, as they are equipped with a "Dead Man's Switch", to prevent movement of a train in the event the operator dies.
A voice-over news announcer reports that blood has been seen coming from the hands of the infant Christ child in the sculpture "The Pieta". However, "The Pieta" does not depict the infant Jesus - it is a statue of Mary holding the dead body of the adult Jesus.
In talking about the End of Days, Father John says that the Gregorian Monks created the Gregorian Calendar in order to be able to correctly identify when the Apocalypse was going to happen (1999). In reality, there is no such monastic order as the Gregorian Monks. The Gregorian calendar was actually named for Pope Gregory XIII, who was Pope when the calendar was first implemented in 1582. The calendar was adopted because the old Julian calendar was slightly too long, and the date of Easter was slowly drifting forward.
During the opening credits several sections of text scroll past in various languages. The last is a section of Hebrew which is clearly upside down.
Subway cars do not have big levers on the outside that will uncouple the cars.
Although we see Satan move into a new body in the film, he goes to great lengths to protect his current one. This is because he's put a lot of effort into this one - he tells Christina that this is the face she's seen all her life, for instance.
Much importance is attributed to the date being exactly 2000 years since Christ's birth. The exact year is unknown, and even the best historians admit that the Roman calendar (which was established many years after Christ's death) is probably off by more than 10 years. However, one of the clerics in the movie 'reveals' that in the movie's universe, the Gregorian calendar was actually set up by the Catholic church so as to let Satan's return occur at the turn of the millennium.
Jericho reads Revelation 20:7 aloud (some were unable to identify it).
As Jericho and Christine exit the subway tunnels into the alley, Christine is wearing booties. Before and after that take, her feet are bare.
When the guys are fighting Christine in the closet, you can clearly see her breast are exposed, then in the same scene when they get a hold of her, her robe is complete perfectly shut and covering her.
The rear view mirror has been removed from the black GMC SUV.
In the subway car an ad for Crazy Eddie's electronics store chain is seen on the wall. The electronics chain went bankrupt and was liquidated in 1989, ten years before the movie's setting.
Glock handguns do not have external hammers to pull back. In several scenes, Jericho can be heard pulling back a hammer on his pistols.
When Satan watches the street punk get hit by the bus, he hear him say 'Nice shirt.' but his mouth says something different.
After Christine gets out of the shower, we hear the director cue her by saying, "Go," before she walks past the camera.
It is said that the Mark of the Beast is "666" but in Apocalypse it was to be inverted, so the real Mark is "999". In the time of St. John number "6" was not in use; it is an Arabic sign and came to use several centuries later.
Satan should not have had much trouble finding Christine. He and his followers could have just waited outside her house and abduct her. He knew where she was and her stepmother likely kept her on a schedule.
The easiest way for Jericho to have protected Christine from having Satan's baby would have been for Jericho to impregnant Christine himself.
Jericho raves at Satan that he is not as evil as Jericho is. Jericho says "You think you 'know bad', eh? Well, you're a fucking choir boy compared to me! A Choir Boy!" instead of the scripted line "You're Choir Boy!"
Satan says to Jericho that it's considered "God's Will" if something good happens and "He moves in mysterious ways" if something bad happens. It's the opposite. If a loved one dies, friends and others will say, " I guess it was just God's Will." When something miraculously fortunate happens, people who suspect divine intervention say "God moves in mysterious ways."