Revealing mistake: When the prisoners commandeer the balloon and proceed to take flight, you can see a television antenna on one of the buildings in the background. (00:07:20 - 00:08:00)
Visible crew/equipment: When the five men are going up the mountain, a crew member is seen beside a big rock, at the bottom left of the screen. (00:33:50)
Continuity mistake: When the two men are carrying water up to their new cave home (via a home made elevator), one of the men is holding two buckets of water. In the shot where you can see the sea behind them, this man hands the second man a bucket of water, which he takes. In the very next shot, from inside the cave, the first man has both buckets and again hands the other man the bucket of water. (00:48:35)
Factual error: It is barely credible that a young Victorian woman like Elena would even think about wearing a goatskin miniskirt - exposing her legs in those days would be akin to walking about topless nowadays. Even if she did those bright yellow cotton knickers - gleefully visible in the scene in the beehive - are in no way from the 1860s. Her pants are a hundred years ahead of their time.
Factual error: The Confederate Army did not take black Union soldiers as prisoners. Those unlucky enough to be captured would be taken back into slavery or, far more likely, simply killed on the spot.
Continuity mistake: When Elena is attacked by the giant bird she is knocked to the ground face up. The bird puts its foot on her and she's face down. A later scene she's face up again.
Continuity mistake: Shortly after they take off in the balloon they had to knock out the Reb. They decide to throw him out. As they reach down to grab him, he starts to wake up. When they bring him to the edge of the basket he's out again.
Continuity mistake: After they've been on the island for awhile, Neb finds a chest floating in the water. It's about 6 feet long, made only of light colored wood and has two wooden bands around it. When Neb pulls it to shore it's a completely different chest. Now it's shorter, made of reddish colored wood and has iron fittings.
Continuity mistake: They flip the giant crab on its back and start to slide it toward the geyser. The next shot is just before the crab goes into the geyser it's now right side up. It hits a rock and flips landing into the geyser on its back again.
Continuity mistake: Nemo's explosion is right under the cannon which are near the back of the pirate ship. Aboard the submarine, Nemo is talking about raising the ship. There is a drawing of the ship on an easel and it shows the hole near the front of the ship.
Continuity mistake: As they are approaching the island, they have to climb into the ring above the balloon and cut the basket loose. It switches back and forth from long shots to close shots. In the long shots, the ring is at sea level bouncing off the waves. In the close shots, they are 10-15 feet above the water and some of them jump into the ocean.
Continuity mistake: After the battle with the crab, Neb has a shirt on. When they climb the volcano he doesn't have a shirt on and doesn't have it with him. They spot the boat and go down to find the women on the beach. Here he is wearing a shirt again.
Factual error: Captain Nemo takes the castaways on an underwater tour around the island, where they observe Greek temple ruins on the sea floor. The ancient Greeks were pioneers of philosophy, politics and engineering, but they never colonized beyond the general area of the Mediterranean and they certainly never colonized the South Pacific (which is the setting of Mysterious Island).
Factual error: All low pressure storm systems generally end up traveling from west to east in the northern hemisphere. So soon after take-off the balloon would have been over the Atlantic Ocean for the next several days. Europe would have been the next large land mass seen.
Visible crew/equipment: As the 5 men are climbing to the top of the volcano, there are several long shots of them crossing large rock formations. In one shot, they are still climbing while in the bottom left-hand corner a shirtless film crew member appears, seemingly unconcerned that the camera is rolling.
Revealing mistake: When the castaways discover two women and a man washed up on the beach, they quickly determine that the women are still alive. The journalist, Gideon Spilitt, checks the pulse of the male and pronounces him dead; but the dead man's limp left hand very noticeably and unnaturally jerks twice just as Spilitt releases his wrist. The actor playing the dead man obviously had an anticipatory reflex action, but they chose to keep the shot in the film, anyway.
Factual error: The balloon that the Union soldiers escape in has no mechanical burner of any type in it that would be needed to keep the craft aloft in the air. A balloon flies by heating the air inside the bag, causing it to rise up. It descend as it cools.
Suggested correction: Gas balloons (using Hydrogen or Helium) large enough to carry passengers were invented in the late 1700s. Gas-filled observation balloons (such as the one in this film) were, in fact, used during the Civil War.
Continuity mistake: Herbert jumps onto the back of the giant bird. In the close shots, he starts to stab it with the knife in his left hand. In the long shots he's holding on with his left arm.
Factual error: At the beginning of the movie they are flying in the balloon for several days. The wind is constantly blowing everything around, hair, clothes etc. I've been in a balloon. Since the wind is blowing the balloon, you are moving at the same speed as the wind, therefore, you don't feel any breeze or wind, it's dead calm.
Continuity mistake: Not long after being stranded on the island, Mr. Spilett is cooking a giant oyster. He cuts a piece with a bayonet and with his left hand offers it to Pencroft who refuses it. He then turns to offer it to Herbert but now the oyster is on the end of the bayonet.
