Continuity mistake: When the members of the League are attacked at Dorian's home, the fight is accompanied throughout by a blizzard of paper falling from a height, yet hardly any of the books have been disturbed on their shelves.
Continuity mistake: The invisible man is seen in one shot with cream covering the majority of the front of his face but it ends towards the middle of his head. When he is in the automobile, the cream is now completely covering his head and neck. Then, when they go to see Dorian Gray, only his face is covered with make-up again.
Visible crew/equipment: When the Nautilus starts exploding after the record is played, there is a shot of things being thrown about in the chamber, and you can see the cables used to pull all the furniture to the left.
Revealing mistake: In the mountain scene where the League is staking out the fortress from a very cold cave, there is no breath to be seen.
Continuity mistake: When the Nautilus leaves London, before it goes under water, the actors are all standing on deck. In the shot where Mrs Harker is talking to Dorian there are chairs on deck (which is quite remarkable for a submarine). When everybody goes inside because the submarine is about to dive, the chairs are gone.
Revealing mistake: When Skinner is walking around in the snow, after he says he's standing outside completely naked, he should have been leaving footprints in the snow. When he does, between shots, they're practically floating.
Revealing mistake: In the scene where Allan Quatermain is waiting for Skinner in the snow and the white tiger shows up, when the camera shows a close-up of Allan, there is snow inside his goggles on his head. If it is snowing hard and the snow inside his goggles isn't adding up, it should have been melting or been melted. But it doesn't change at all, which proves it to be fake snow. How did it get in there anyway?
Visible crew/equipment: When Hyde is first brought aboard the Nautilus, he is loosely chained, but still tossing crewmen about. There is one crewman, whose back is toward the audience, whose striped shirt puckers around the harness as he is jerked backwards.
Factual error: In the first few scenes they show some newspapers. They show Tuesday April 10, 1899, then Thursday May 18th,1899. If April 10th is on a Tuesday, then May 18th can't be on a Thursday, it would be on a Friday. April 10, 1899 was actually a Monday, but May 18th that year was indeed a Thursday.
Revealing mistake: In the scene early on in the movie where Quatermain fights the goons in the bar, it is quite easy to notice when it is Sean Connery, and when it is his stunt double.
Continuity mistake: Mina's hair turns curly whenever she is in vampire mode EXCEPT when she is in Dorian's library and attacking the goon who held a knife to her throat.
Continuity mistake: When the Phantom's men ambush the League at Dorian's residence Sawyer is seen joining them in revealing themselves and aiming at the League (you can tell it's Sawyer by his clothing and weapon). Then during the Phantoms speech Sawyer reveals himself again as if he was never there.
Deliberate mistake: After Mina leaves the car in Venice, Sawyer just manages to avoid several obstacles on the way, including a bend in the canal. But in the first scene, where Sawyer swerves the car around, its front should have slipped into the water anyway, considering the speed of the car and the tightness of the street, which makes a sharp L-turn at such close quarters next to impossible. But then the scene jump-cuts, and the car is well past the hazard.