At the beginning of the film, as the bride and groom drive away, their car alternates between a 1957 Buick and a 1958 Plymouth.
When the child stops the married couple with his itch light, the scientist drives up in a white 1964 Corvair convertible. When the child and scientist drive off, however, they are in a different car.
The Air Force helicopter that flies around Yonggary in the film is a Sikorsky H-19, but the interior bears no resemblance to a real H-19. There is no room in an H-19 cockpit for anyone to sit anywhere but in the two pilots' seats. The area behind these seats is filled by the rotor transmission, not by electronics and added seating. Other aircraft occupants ride in a separate cabin behind and below the cockpit, and the two compartments are connected only by narrow access holes next to the pilots' legs.
When Yonggary breathes fire out of its mouth, a clearly visible cylindrical metal nozzle replaces its wagging tongue.
The debris that falls on Iloo comes from well above and to the right. The rock that wounds him comes from the left and moves almost horizontally, meaning it was thrown.
When the Jeep speeds past Yonggary's feet, several cracks are visible in the Yonggary suit's tail.
When the photographer's Jeep plummets down a hillside, the Jeep is a miniature, but the hill is not.
Several scenes in the film combine footage shot on a miniature set with location footage shot outdoors, leading to mismatches in scale (for example, during Yonggary's first attack on Seoul, people fleeing down a street with miniature buildings lining each side all appear to be about two stories tall).
When Yonggary cuts the military Jeep in two with its horn's laser beam while it is driving down the road, a smaller support wheel used to support the front half of the Jeep is clearly visible.
In many scenes in the film, when Yonggary breathes fire out of its mouth, the pipe used to pump the fire out is visible.
During the film's opening credits, the starry sky has an obvious textile square pattern.
When Yonggary walks by the camera in one scene, the camera tilts up to show a camera light and space above the sky backdrop.
In several of the film's helicopter shots, the wires holding up the model are clearly visible.