Factual errors: Hannah Ásgeirsson is a man's name. In Iceland, a person's last name is derived from their father's first name. Her father, Sigurbjörn Ásgeirsson, is the son of Ásgeir. Her last name would be Sigurbjörnsdóttir, daughter of Sigurbjörn. Plus, no Icelandic word or name ends with an H. Therefore, her name should be Hanna Sigurbjörnsdóttir.
Factual errors: Twice, the explorers run across veins of free metallic magnesium in the ground. Magnesium is extremely active chemically, and is only found in compounds.
Continuity: When Trevor Anderson looks at the book in his flat, the front cover reads Journey to the Center of the Earth. Moments later, as he is flicking through the same book, the page headings read Journey to the Centre of the Earth.
Continuity: Over the course of the movie, the main characters leave their backpacks behind only to have them suddenly reappear in the next scene. For example, when they get to the bottom of the tunnel after the mine, they drop their bags and walk through an opening without them. Several minutes later they are seen walking with them.
Continuity: In the scene where Sean is laying on the "beach" after being carried across the ocean by the kite, when he is laying down, he is shown to have gloves on. In the next shot, as he is standing up, the gloves are gone. In the next shot, he is taking the gloves off and in the next shot, they have disappeared again as he begins to follow the bird.
Continuity: The sweat on Trevor's, Sean's, and Hannah shirt, from the giant mushrooms and up to the "sunset" scene on the beach, keeps disappearing and reappearing.
Continuity: In the scene where the explorers end their exciting 'ride' in the mine, Hannah rolls over and has a loop of the rope over her right breast. Seconds later, the rope is gone.
Continuity: As Trevor is looking through the book in his flat, as the shot jumps from in front of him to the over-the-shoulder view, he is reading a different page in each shot.
Factual errors: A steam geyser capable of lifting a boat with 3 passengers several hundred meters would scald the passengers to death.
Factual errors: A rock wall contains raw diamonds, rubies, and emeralds. The diamonds are clear and already cut. They should look like dull yellow pebbles.
Factual errors: One character finds himself walking across a chasm on magnetic rocks that float on a horizontal plane and bump off one another like bits of flat wood. Magnetic poles either attract or repel, so the rocks should either snap together or repel from one another, spin, then snap together. Even if large, flat magnetic rocks somehow found a natural equilibrium between their weight and magnetism, the weight of a person walking on them would destroy it.
Continuity: After falling down a huge tunnel filled with water, despite being soaked to the skin, Trevor's version of his "Journey to the center of the Earth" book is completely undamaged. Even his brother's notes survive.
Factual errors: Sean tries to use his cellphone right after entering the cave and there's no signal. Later on, in the center of the earth the cellphone rings and he chats with his mom.
Factual errors: The three gems found in the tube are emeralds, rubies and diamonds. Except in placer deposits (eroded sands containing gems), these three compounds cannot be found together, particularly in metamorphic rock since diamonds only exist in igneous rock.
Factual errors: Josh's cellphone is a Motorola but the ring is clearly a Nokia Sound.
Errors in geography: Hannah says "there are no roads to the north". If by that she means there are no roads leading to the Snaefells Glacier she is wrong. You can actually drive (on a regular Ford Focus family car) to within 500 meters of the top of the glacier.
Continuity: When Sean is crossing the magnetic rocks, one rock rotates in a complete circle a few times. When it's rotating, his pocketknife falls from his side. But in the next scene, it's back on his belt.
Factual errors: In the scene where the explorers are within the tube, Trevor tries to light the magnesium with a flare, only seconds later, the flare is out. Flares would usually last around fifteen minutes.
Revealing mistakes: Throughout most of the movie, all three characters aren't sweating in 103 degrees Fahrenheit and in tropical conditions.