Though Simone, a 17th century Frenchwoman, speaks English with an adopted French accent, Stana Katic actually can speak French, and it is one of five foreign languages in which she's fluent.

A plesiosaur can be seen swimming in the pool in the last shot of the library floor. In a later episode of the follow-on series, Jenkins mentions that the largest animal they have in the library is Nessie, a.k.a. the Loch Ness Monster. Nessie believers have speculated that the monster might actually be a plesiosaur.

The Judas Chalice prop later appeared in the Leverage (2008) episode "The First David Job (2009)". Both projects were produced by Dean Devlin.

During the swordfight, Flynn's stance is that of an epee/foil fencer (with his off hand held above his shoulder); his opponent uses a saber fighter's stance (with his off hand on his hip).

Establishing shot of Glenn Estate shows a white castle-like building. That was the Louisiana State Capitol Building from 1852 to 1932. This Baton Rouge landmark is now a museum.

Continuity

As Flynn is sitting in the barber chair, the shave cream changes between shots.

When talking about the chalice Flynn says it is made from the 30 pieces of silver but later in the scene Judson says the aversion to it is due to the original 13 pieces of silver.



Factual errors

Datura hallucinations are quite different from what is depicted in the film. Although, seeing someone grow an extra finger, for example, is possible, Datura is more along the lines of temporary psychosis. The most common hallucinations would be seeing people who aren't there, hearing voices, having conversations with people who aren't there, and seeing inanimate objects move and float. The character in the film would have never been able to remain so coherent after consuming a fairly large Datura tincture. In reality, he would be extremely paranoid, probably running from or grabbing at his hallucinations.

In the film, the "crest" of Vlad shows the letter "V." This should have been the letter "B," as the Cyrillic alphabet spelling of Vlad is actually Blad. The B is pronounced as V.

When Flynn sizes up the slot in the mouth of the Dagger Man, he says it's about three quarters of an inch in diameter, making the nearest comparable modern coin a silver dollar. However, a silver dollar is more like an inch and a half in diameter; a dime would be closer to three quarters of an inch. He probably meant "radius" rather than diameter.

Flynn fends off the henchman with the gold hand, he uses the stone to turn a cushion into gold. He then whacks the henchman and hands off the cushion to the auction house's cashier. A mass of solid gold the size of that cushion would have been too heavy for an average person to lift, much less whop someone upside the head with one hand.

When Professor Lazlo is describing Vlad in his lecture, he calls him Dracula, and explains it means Son of the Dragon, Son of the Devil. Vlad was really known as Dracula because his father, Vlad II, was called Dracul. This was because he was a member of the Order of the Dragon, which was founded to protect Christianity in Eastern Europe.



Incorrectly regarded as goofs

If they knew the Philosopher's Stone was inside the vase and had the power to turn anything into gold why was Charlene worried about going over budget? They could have paid any amount and then used the stone to make any amount of gold to cover what they spent, and more besides. Charlene explains that they don't use the artifacts for personal gain, and that would absolutely be for personal gain.



Anachronisms

Simone could not have been an opera singer in 1628 at the French court. The only prominent operas at that time were Italian. Louis XIV hated the Italian style and would not have employed singers at court to perform it. The first French opera was enacted in 1671 followed by a rich and opulent opera tradition at the French court.



Audio/visual unsynchronized

As Flynn enters the barber shop you see a man playing guitar. The music that you hear is a basic blues rhythm that is played with a (metal or glass) slide on the left hand. However you clearly see that the man does not have a slide on his fingers and furthermore his left hand rarely moves. It is impossible to get the tones that you hear without a slide and without more frequent hand movements with both the left and right hand.



Errors in geography

Aspen trees are native to the northern parts of North America and the western mountains. They require cool summers (not found in New Orleans) to thrive. It is unlikely one would be growing in the swamps of Louisiana.



Plot holes

When Flynn and Simone are trapped on Jean Lafitte's ship much is made of the fact that they are sealed inside a room with solid walls and that their only hope of escape is by breaking down the door with a cannon. Yet, when they are setting up the cannon the stern windows of the ship are clearly visible behind them. All they would have to do is smash the glass and crawl out.

It is inconceivable that a vampire could stay undercover as a university lecturer since he would be required to work in the daytime, have all sorts of meetings etc.

On Lafitte's ship, Simone's excuse for not using her vampire strength, magical teleportation ability etc to fight their way out or break down the door is she supposedly hasn't fed in 24 hours. However, when they are caught again, she doesn't use her abilities against Kubichek and his henchmen, even though a little while earlier, she is explicitly shown taking blood bags out of her stash and later she uses them to fight Vlad. Earlier, she could have just mopped the floor with the bad guys and avoided all the unpleasantness.

The Library contains all kinds of powerful magical artifacts, including the sentient sword Excalibur which has a will of its own and is able to float and fight of its own accord. Yet they send the Librarian out on the most dangerous missions, to literally save the world, without even supplying him with any conventional, technological equipment, let alone magic gimmicks.



Character error

The town of Jean Lafitte is actually connected to the Barataria swamp, which is called the Barataria Preserve. It would have never taken them what appeared to be a day's ride from anywhere in New Orleans to reach Lafitte, it would be less than a 2 hour boat ride.

When Flynn is explaining Jean Lafitte to Simone, he says, "we must be near the Betararia swamp". The correct pronunciation is Barataria swamp. Flynn, as a philosopher with his vast knowledge, would have known the correct pronunciation of the word simply from the spelling of it.

In the cabin of the ship "Pride", Kubichek fends off any vampiric attack by Simone by holding up a cross; however, she showed no adverse reaction on seeing a cross-shaped warning sign at the entrance to the swamp, nor does she react later when Carson holds up two knives (presumably made of silver) in a cruciform shape - in fact, she defies a vampire's supposed aversion to both the shape and the metal by knocking the knives out of his hands.