Visible crew/equipment: When the airplane flies over the area where the saucer skidded in and became buried in the ice, you can see the equipment used to clear the snow and smooth out the ice (at the narrow end of the ice). You can also see the tracks from the machine criss-crossing the circular portion from the aerial shots. (00:16:20)
Visible crew/equipment: When the scientist finds the saucer near the North Pole, the panorama of the sky reaches only to a certain height. When the camera pans upward, as the smoke billows up from the explosive charges, the backdrop of the sky disappears and the real sky appears above the Hollywood backlot. (00:22:55)
Visible crew/equipment: When Bob approaches the door to the greenhouse with a geiger counter, the wire to the device can be seen trailing out the bottom of his pants leg on onto the floor.