The opening scene shows M (the bad guy) attacking several countries & planting false evidence that makes it look like other countries have attacked them; the result is a massive world war is about to start.
A tank rolls up to some men at a roadblock. The men at the point yell for the tank to stop, but it shoots at them then rolls over their dead bodies.
One scene involves a massive bar fight. After the fight, the man responsible escapes; a man rushes out of the bar, shoots the man in the arm (on purpose, he wants to interrogate him), but when he reaches the man he finds he has swallowed a poisonous pill that kills him.
There is a big fight scene that takes place in a library. A man shoots another repeatedly in the chest with a machine gun (it doesn't hurt him; he's immortal). Several men are shot with guns in this scene. One man viciously attacks several people with a sword & some mixed martial arts. Skinner removes his clothing, making him invisible, & procedes to attack several men with various objects laying around the library (books, oil lamps, etc.). After the fight a man grabs a woman from behind & tells the men to drop their weapons or he'll kill her; she procedes to turn into a vampire, spins around, grabs the man, forces him on the ground & sucks his blood (when she stands up she has blood all over her face).
When Allan & Tom go to hunt down Dr. Jekyll & ask him to join the League, they find him transformed into Mr. Hyde, jumping across the rooftops of London. They chase him from below, shooting the rooptops, trying to make him fall into a trap they've set. When he finally falls into the trap, it takes him inside of the Nautilus (Capt. Nemo's submarine). Once inside several men try to restrain him with chains, but he throws & tosses them around the room.
During one scene in Venice, the League must try to stop a series of bombs hidden in the canals; if they don't all of Venice will explode. Several of the buildings are blown up before they can stop the chain. For the majority of this scene, three men & a woman are driving through Venice in a fancy car; they are frequently shot at by M's henchmen. One of the men jumps out of the car at one point to attack some soldiers. The woman turns into a vampire, flies out of the car & together with a swarm of bats attacks several men. The final two men alternate driving the car & shooting at soldiers.
During the final major moments of the movie, there is nothing but fighting in a Russian explosives plant. Several scenes of intense violence take place here: Skinner while naked, attacks a man who has a flamethrower; the man turns around & blasts Skinner with the flamethrower. Skinner runs away screaming; later when Tom finds him he is huddling in a corner whimpering. He is now visible from where his skin was burned (very graphic). One man drinks a whole pitcher of Dr. J's formula; this turns him into a huge & disfigured version of Mr. H. He then becomes involved in a major fight with Mr. H & Capt. Nemo. Capt. Nemo attacks his giant fist ferociously with his sword, bloodying the giant's knuckles.
Towards the final moments, there is a big fight scene between two of the characters. One stabs the other through the heart; he presumes the other to be dead, but after he pulls out his cane/sword & exits the room, the other character comes back to life, stabs the character through the stomach, pinning him to the wall. She then procedes to show the man his picture, which makes him crumble into a skeleton, & then a pile of dust.
Tom shoots a man through the back, killing him.
One of the main characters is killed by M.
Overall, 5/10 for violence/gore (moderate).