Revealing mistake: When The Mask is dancing with Tina and he turns her into a human tornado while spinning her around, none of the onlookers in the crowd show the slightest bit of amazement at the impossible feat that just occurred in front of them, indicating that the extras were not directed to react to the special effects.
Revealing mistake: When Draven sends T-bird to his death in his car, the real Ford Thunderbird is replaced by a fake mockup using a flimsy one-piece fiberglass body mounted on a pair of straight axles. When it explodes, the body lifts off in one piece, warping wildly while the front axle simply falls away. No proper car components like engine, transmission, suspension and so on, are seen anywhere, though they should be. (00:57:05)
Revealing mistake: In the big wheel, the boy falls out and grabs Axel's leg. When it zooms out, it is a man climbing his leg.
Revealing mistake: At the beginning, when they have just robbed the bank, the fat guy slides down that shoot on the outside of the building as the get-a-way car pulls up to meet him. If you look closely at the road before the car stops, you can see skid marks left by the car in previous takes.