Revealing mistake: In the office tower after the quake there is a panic and workers rush down the stairs only to find them fallen away. After two women fall to their death a man is left hanging on a girder, but falls onto a giant piece of glass. Look at the top of the frame and you will see the airbag shooting our from under it.
Revealing mistake: When the airplane is coming in for a landing, we see an exterior shot of the plane shaking violently well before it has touched down. Clearly the "earthquake" effect is achieved by merely shaking the camera.
Revealing mistake: During the quake, a mother is seen having a plate glass window fall on her face while her daughter screams. Before the mother turns around to show us the gore, look close and you can see a shard of glass already "placed" in her face before the fake glass falls her. Additionally, while not a "mistake", it's clearly a "stuntman" portraying the mother. The face and yelping give it away.
Revealing mistake: After failing to spin the loop in the motorcycle the first time, Miles tries again. He starts driving towards the loop, and after he finishes the first half, if you look carefully, the bike then falls out of the loop. For the rest of the scene, he continues to ride the bike around the second half of the loop anyway. The shot of him riding towards the loop was probably a previous take.
Revealing mistake: During the scene on the freeway during the earthquake, a truck carrying cattle drives off the road. When it does, the cattle it's carrying do not so much as move, let alone get ejected from the vehicle.
Revealing mistake: When the parking lot building collapses, check the right side where the cars are. All along the ground level there's a rectangular strip where the film of the miniature building was pasted on top of the film with the real-sized parked cars. Note how all the debris falls behind that strip, it never falls on top of the cars, as if there was a weird black hole of some sort. (01:37:54)