Gaffes

The characters dived into water several times, yet many scenes after their dive into the water show their head hair completely dry when they should be wet.

After Scarlett heals the wound on Souxie's arm with the stone, Souxie's sleeve is left bloody and with big holes in it. When they've gone through the underwater tunnel and are approaching La Taupe, Souxie's sleeve is clean and there are no holes in it.

When George tells Benji he was in a jail in Turkey, you can see Scarlett walking behind him (11:30) however, she's shown in front of him again in the next cut.

The poem on Flamel's stone shouldn't rhyme in English.

Scarlett Marlowe incorrectly attributes the inscription 'Abandon hope all ye who enter here' to mythology. In fact it is a translation of the inscription over the gates of Hell in Dante's 'Divine Comedy'.

At the opening of the movie, Scarlett tells the camera she is about to enter Iran illegally, and if she gets caught, the penalty is stoning! That is not true; the stoning (which rarely happens in Iran) is the punishment for adultery.

At the beginning of the film, Scarlett is reading the wall that she then breaks. Middle Eastern languages are read right to left, not left to right. Scarlett reads the inscription backwards.

The headlamps the characters wear are upside down. This was most likely done so the light didn't shine into the cameras.

In the catacombs all the main characters wear headlamp/camera combinations. The headlamps point upwards, yet the "footage" the are supposed to film is pointed downwards.

The headlamps used are all clearly on their lowest settings at all times. if they were at the highest or even "medium" settings, they would have illuminated the entirety of the confined spaces that the characters were in.

This was likely done to maintain some of "spookiness" that the film requires.

The burning car the group encounters very obviously has absolutely no interior whatsoever aside from fully-stripped seats.

Everyone in the party is wearing basic city street clothes / shoes and zero safety gear, not something an experienced archaeologist would do, much less someone experienced with the environment they encountered.

During the movie, the cast accidentally enters hell when exploring the Catacombs of Parks. This is a mistake, as they had already entered hell as soon as they arrived in Paris.

When they show the house of Flamel, they show that the house is on rue de Flamel, this is not true. Flamel's house is on 51 rue de Montmorency, rue de Flamel is only named after him.