Revealing mistake: When Francis emerges from the cave, he stands in the foreground, with the distant mountains and sun in the background. The sun creates a lens flare, which is an internal reflection within the camera lens. Yet Francis is in front of the flare. This shows that the actor was composited with the background via a traveling matte process.
Revealing mistake: In the carousel scene, when the contestants are starting to float into the air, you can see the cables attached to the contestants that are lifting them up. (00:08:58)
Revealing mistake: When the dome city starts to blow up, people are running around in a panic. One man in a red outfit jumps off a balcony to the next floor and you can see a modern (1970s) lit exit sign over a doorway behind him. Many of the interior shots for the dome city were filmed in a large shopping mall; that sign must have been missed when they were trying to make it look like the year 2274.