FAQ

It is assumed it was Papillion's brother or friend who died in the car that was on fire. This was Papillion's "demon" who actually pulled Papillion into the car in the catacombs and killed him. So as with the female cult leader and "the mole" it seems he was either that person's spirit in physical form or a demon in the shape of the person to lure them below.

It is strongly suggested as the group crawls through the tunnel with an inscription George reads as "Abandon all hope ye who enter here". Which Scarlett then responds with something along the lines "...and they would be made to crawl on their bellies into the darkness of hell". It is after the group emerges from this tunnel that things begin to go particularly wrong.

It is left completely unexplained. It is not mentioned that they were devil worshipers nor satanists, though.

It is assumed that it is Scarlett's dead father calling (because he killed himself by hanging as he is seen at the beginning of the movie during the bombardment) asking her why wouldn't she talk to him. He is referring to the night he killed himself, after he tried to call his daughter but she wouldn't answer, as she tells him near the end of the movie when she sees him again and apologize before he disappears.

There are multiple theories. The literal interpretation of the ending is that they resurfaced by continuing downward as suggested by the "mole" friend who had been living in the catacombs for two years. While logically this doesn't make a lot of sense, the group did experience paranormal events, which you kind of have to suspend disbelief for anyway. Another interpretation of this ending is as the movie is titled "As above, so below". The surface world descends into the catacombs. As Scarlett states that this means there is an inverse for what is above (i.e., when they find the "doorway" in the water puddle). Given that the world descends into catacombs, once the group crosses the (supposed) gates of hell everything becomes the inverse of the world they came from. Therefore in order for the group to escape, they would need to descend from the catacombs into the world. This may imply the survivors are now in an alternate version of the world or perhaps even in hell.

No, it isn't right. The Archaeologists are investigating Nicholas Flamel's records, so it is 741 times whatever measurement he was using. The Metre was introduced by the French Revolutionary Government in 1793, five hundred years after Flamel, so he would not have been using that method of measurement. The Imperial Foot was standardised in the 1950s, so he wouldn't have been using that measurement either. However, the pre-revolutionary measuring system, the "Ancien Régeme" used the "Pied", which like the Imperial "Foot", was based on the Ancient Roman "Pes" (all of which mean "foot"), but every region had their own standards. The Pied de Paris was the standard measurement in Paris at the time of Flamel, and was equal to 1.0687 modern imperial feet, therefore if Flamel used this system, Hell would actually be 792 imperial feet (241.4 metres) below Paris, which is 51 feet deeper than stated. Alternatively, since Flamel was an alchemist, he would probably have used Greek measurements, as did later alchemists. In which case he would have been measuring in "Pous" (which also means "foot"), but which was equivalent to 1.0111549 imperial feet. In this case, Hell would be 749.4 feet (228.4 metres) below Paris, which is 8.4 feet deeper than stated.