Revealing mistake: In several scenes Superman has fillings in his teeth.
Revealing mistake: During the subway scene, when the first pillar breaks and starts to move towards Dorothy, the top of it is cardboard and wiggles back and forth as the pillar breaks. This is noticeable in the other pillars as well.
Revealing mistake: As the huge guardian goes to move off and chase Elle and Stella, you can see its shadow cast on the fake backdrop sky.
Revealing mistake: When Tony is stacking the wine barrels in Gannon's lab, you can see the wires pulling the last barrel up into the pyramid.