Revealing mistake: When Hightower is in the Monster Truck you can see that a white stuntman is actually driving it in one of the shots.
Revealing mistake: When Fackler is directing traffic due to the blackout, many moths start circling the lights he holding. Many of these moths are actually attached to strings.
Revealing mistake: During the chase with the bus with Harris and Procter on board, they take a detour by smashing through a fence so they don't hit a load of cars. Behind the cars, you can see the ramp to give the bus a bit of a lift through the fence.
Revealing mistake: Hightower reacts too early to the big goons' punch in the warehouse.
Revealing mistake: When commandant Lassard and Spacler walk into the bar all the guys in there throw their weapons behind the counter, but if you look at the weapons they're all plastic props.