(at around 1h 20 mins) After Prof Anderson has ignited the magnesium seam in the magma pipe causing the water to pour into the pipe and generate a steam geyser, the trio can be seen lying in the bottom of the T-Rex jaw as it hurtles towards the surface at great speed. At first, despite the speed, the trio's hair (particularly Sean's) is hardly moving from the wind. The next moment, as Sean declares, "This thing's heating up." you can see that their hair is waving around wildly.
Backpacks tend to reappear at certain important plot turns and such. For example; when they first discover the world at the center of the earth, they throw away their backpacks and continue on without them, then, however, they reappear again prior to leaving on the raft and then while on the raft they are gone once more only to reappear once again prior to meeting the dinosaur. As for Sean's backpack, it is clearly missing when he is jumping the floating rocks and then at the end it reappears when they have landed the dinosaurs skull in Italy. Furthermore, no one is seen carrying an extra backpack at any time, maybe suggesting that the other two carry Sean's pack.
(at around 1h 18 mins) In the scene where Prof Anderson, Hannah and Sean are stuck in the magma pipe in the T-Rex jaw, Prof Anderson tries to ignite the magnesium with a flare. He instructs Hannah and Sean to hold his legs so he can reach further down the magma pipe. As he holds the flare to the rock face you can see that the T-Rex teeth are at chest height, indicating that he is not leaning far out of the jaw. When he tries to get back into the jaw you can see the teeth are at waist height now.
(at around 1h) When Sean is lying on the "beach" after being carried across the ocean by the kite, he is wearing gloves. In the next shot, when he is standing up, the gloves are gone. In the next shot, he takes the gloves off. In the following shot, as he begins to follow the bird, they are gone again.
(at around 33 mins) When Hannah rolls over at the end of the ride in the mine, a loop of rope is over her right breast. Seconds later, the rope is gone.
(at around 1h 18 mins) When Trevor tries to ignite the magnesium with a flare, he claims that it's "...too wet...". Magnesium burns in water, producing magnesium oxide and hydrogen - in fact, pouring water on burning magnesium intensifies the fire; the most effective way to douse a magnesium fire is to cover it with sand or dry dirt.
(at around 1h 6 mins) Sean walks 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.
(at around 29 mins) A diesel generator that was abandoned 60 years ago would not start by simply pushing the starter button; the batteries would be totally dead.
(at around 37 mins) When falling down the entrance shaft, they yell at each other. It would be impossible for them to hear each other. Skydivers in the same situation cannot communicate with each other verbally due to the wind blowing up away from their faces and would not carry over to another person. The TV show MythBusters (2003) proved verbal communication in such a situation is impossible.
A steam geyser capable of lifting a boat with 3 passengers several hundred meters would scald the passengers to death, and the accompanying G-forces would flatten them into pancake smears.
(at around 1h 16 mins) A T-Rex skull looks like it can't float; the eye sockets and nostril would let in water. However, the T-Rex's skull is a honeycombed lattice, not solid bone, to provide both strength and flexibility. Theoretically, there could be enough air pockets to make the skull float.
In neither this movie nor Journey to the Center of the Earth (1959) nor the source Jules Verne novel, does anyone get anywhere near the literal "center" of the Earth. The title is only a metaphor, like "the sun rises in the East" - it's useful for describing what we see, but is not scientifically accurate. We know this for several reasons. 1) It is not known how long Trevor, Hannah, and Sean fall (after the talk about water and stalagmites, they continue to fall and scream, and then it fades to later), but it's definitely not a day and a half, which is how long they would need to fall to reach the actual center of the earth. After a few seconds of falling, they would reach a terminal velocity of about 120 miles per hour, so a 4000 mile fall would take about 33 hours. However, this is true only if they go to the actual center of the planet. Since the Earth's core is molten metal and rock, it's obvious that they don't travel that far. 2) The pressure at the center of Earth is believed to be 3X10 to the eleventh power pascals. The pressure at sea level is approximately 101 kPa, meaning anything from the surface would be crushed by the enormous pressure of the Earth's center, and anything from the center would collapse when exposed to the pressure of the surface. So Trevor, Sean, and Hannah would have been crushed to death, and the blue bird would not have been able to live, let alone fly. 3) At the direct center of the earth, the mass of the earth is equal in all directions. As such, the gravitational force would be equal in every direction such that it would seem to the group that there was no gravity, and they would float. 4) In the climatic scene near the end, in the magma pipe, the magma pipe extends farther down with magma rising up out of it, indicating that the actual center of the earth is still farther down.
(at around 1h 18 mins) In the tube, Trevor tries to light the magnesium with a flare. Seconds later, the flare is out. Flares usually last up to 15 minutes, but they can be smothered.
The Giganotosaurus is bigger than its fossilized forebears in the Cenomanian Stage, 96 million years ago. The size increase could have happened in the intervening years.
(at around 13 mins) While Sean is Googling in the airplane, he types without an on-screen keyboard. The PSP's only method of text input is through the triple-tap on-screen keyboard.
(at around 31 mins) When racing down the mine track, all three of them have to quickly duck. When Hanna ducks she leans on the handle on the handcar and raises the other end into the wooden beams, and it does not collide - obvious CGI in use.
(at around 31 mins) On the mine track there are several scenes that show Hannah riding the handcar with the handles remaining still. They would be going up and down while the wheels were turning.
In the scene on the beach, where Trevor is reading to Sean from Max's notes, the main light source is orange on the right side of Trevor's face, with purple light on the left side. However, looking at the same scene from behind, the main orange light source is again on the right and the purple on the left.
(at around 36 mins) When they first realize they are standing on the muscovite when the camera pulls back and above there is a heart traced in the muscovite just behind Trevor.
(at around 33 mins) When Trevor and Hannah's mine cart crashes into the wall, cables are briefly visible in the middle of the tracks.
The Snæfellsnes Peninsula, where the party makes its descent, is a volcanic zone. They wouldn't be able to get very far down without reaching lava.
The journey of Trevor, Sean, and Hannah under the surface of the earth only lasts hours, yet they travel arduously from Iceland, place of descent, to Sicily, where the steam geyser brings them back to the surface, a distance of about 3700 km.
The journey of Trevor, Sean, and Hannah under the surface of the earth only lasts hours, yet they travel arduously from Iceland, place of descent, to Sicily, where the steam geyser brings them back to the surface, a distance of about 7800 km.
(at around 1h 8 mins) Apart from the fact that the existence of the zero-gravity "magnetic field" which Sean reaches is implausible, everything seems to float around there, including the rocks and even Sean's Swiss Army knife. Although, Sean doesn't and is still subject to gravity and in danger of falling into the abyss. His head torch also drops into the chasm while he is clinging to the overturning floating rock. However; the pocket knife is metal, and is it plausible then that to an extent that the rocks are too (as they are "magnetic", and therefore likely metallic). Sean and his head torch are not, therefore would not be able to float as they are not a part of the floating magnetic field.
(at around 17 mins) Hannah says "there are no roads to the north". If she means there are no roads to the Snaefells Glacier, she is wrong. Anyone can drive a regular car within 500 meters of it.
(at around 1 min) In the opening, Trevor is explaining continental drift to a class while he plays a video. However, the video shows India moving westward across the Indian Ocean and colliding with Africa. This video is playing in reverse.
(at around 41 mins) Trevor identifies the luminous birds as a species that went extinct "...150 million years ago." However, the oldest known bird, Archaeopteryx, emerged between 150-145 million years ago, meaning that the luminous birds went extinct before birds began.
(at around 11 mins) Sean mentions "booking a flight to Reykjavik". International flights going to, from or through Iceland use Keflavik Airport. The airport in Reykjavik is what most countries would consider a regional airport, unable to handle large jetliners.