Continuity mistake: When Gray stabs Mina and pulls the sword out of her body the blade is clean, only in close-up when he wipes it there are blood stains. (01:28:00)
Suggested correction: The stains are only at the top end of the blade. We don't see the blood because the part is embedded in her.
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. (00:29:20)
Suggested correction: Because she doesn't go "Vampire mode." She simply sucks his blood.
She's can't suck his blood without turning into a vampire. Her "vampire mode" includes having fangs used for sucking blood.
She is able to control her transformation. She's progeny of Dracula himself. She's extremely powerful.
Plot hole: What on earth are those sailors doing with Hyde when he is chained up on The Nautilus? He is solidly chained to the floor and walls and they keep stepping up to him to allow him to swat them out of the way, risking injury or even death. They stand around like idiots as if waiting their turn to walk up to Hyde and be belted across the room. Why? Why are they even there? Hyde doesn't need subduing, and if he needed guarding they could do it without getting into range.
Suggested correction: They are there to subdue him because he is strong enough to tear the chains from the walls, which he does seconds after they stop trying.
Continuity mistake: When Mina bites the attacker at Dorian Gray's house for the first time there's blood all over her face, but after she bites him the second time it's gone before she had a chance to wipe it off (even that wouldn't have removed the blood so completely). (00:28:25)
Suggested correction: We don't see what she does when she's down though. Whilst you are correct you could be forgiven for believing that she may give word her face on his clothing.
Continuity mistake: When the men attack Quatermain in Africa, at one point he hits one guy with a bottle. The bottle completely shatters and there's nothing left to hold. When it cuts back to Quartermain, he's holding a big piece of a broken bottle.
Suggested correction: You can see the bottle in his hand in the scene where it shatters.
No, you can't. The bottle completely shatters. Then in the next cut he's holding the bottle.
Continuity mistake: How can the invisible man cover his face with white cream so we can see him, but his stubble is visible throughout the movie as dark brown only when he has the cream on his face? It can't be because cream's on it, because then it would be white. (00:19:55)
Suggested correction: This is likely a lighting issue as the actor is famously red haired.
Plot hole: When the Nautilus is in Mongolia, we are shown that there is deep snow everywhere. If this part of the movie takes place in July or August, why would there be any snow at all? Even the Yukon doesn't have snow in the summer, except for the northernmost portion of the province. (01:15:20)
Suggested correction: Mongolia is known for wildly changing weather patterns. Sudden snow or hail is common there, they are at an elevated position and is also set more than a hundred years ago.