Revealing mistake: In a scene where the canoes are shooting the rapids through a sheer cliff you can clearly see a stuntman climbing out of the water onto the rock.
Revealing mistake: When the ship is upside-down and they're trying to get Susan down from the table, you can see that the table really isn't attached to the ceiling. You can see the center pool split into legs that are supposed to be connected to the floor, but when Susan moves around and shakes the table, the legs shake and you can see space between them and the floor. Even if the other legs outside of the shot were connected, the table would be leaning under Susan's weight.
Revealing mistake: After Alice falls down the hole, into the leaves, she gets up and runs down a stone to follow the White Rabbit. As she runs down the stone, it quite visibly squashes down under he feet, revealing that it is foam.
Revealing mistake: Freeman Lowell has several cargo containers dumped off the spaceship, to make it appear the ship has suffered an accident. A wide shot shows the ship receding in the distance, with the containers rolling weightlessly in the foreground. As the foreground containers pass slightly in front of the more distant ones, they don't mask them; their images overlap. The containers were apparently composited into the shot with simple multiple exposures. (00:35:40)
Revealing mistake: When Anguirus makes his sacrificial charge against Gigan, the hand that is moving the Anguirus costume can be seen holding it.
Revealing mistake: In the opening scene, when the soldiers and slaves march down the mountain, as the carriage containing Aguirre's daughter passes by the camera, one of the soldier extras just behind the carriage looks directly at the camera. (00:03:38)
Revealing mistake: When Itto and Daigoro are walking through the forest, just before they are attacked by the group of male ninjas, there is a wide shot and on the left side of the screen you can see a number of cars pass by. (00:31:50)
Revealing mistake: At the end of the film, in the extreme close-up shot of the Dual Flintlock pistol Ronin having his forehead hacked by Itto's sword you can see his hair is a wig. (01:20:27)