Revealing mistake: In one of the final scenes where Stallone is hanging out of the Statue of Liberty, you can see that his "JUSTICE TATTOO" on his upper arm is a fake. You can see at the edge of the tattoo that it is glued on the skin.
Revealing mistake: When Fergie is given his work detail and address at the start of the film he walks through the door and sees Mega City. Look at the live traffic at the bottom of the screen - the same shot is used again just as he boards the yellow shuttle. The traffic queue is the same vehicles in the same order.