Revealing mistake: When the Oceanic 747 attempts to make its first landing, you can tell that the 'hole' on the side of the aircraft is simply painted on.
Revealing mistake: Because the hijacked plane is carrying deadly chemicals, the military officers at the Pentagon plan to takeoff urgently within 1 hour. Yet when they reach the airfield you can see palm trees and mountains in the background. If the meeting was in Washington DC, they'd need to takeoff from a nearby airfield. 1 hour is not enough time to get from Washington DC to any airfield with palm trees and mountains. This scene was probably filmed in California.