Revealing mistake: In the scenes where Riley is using his computer to look up information on the "SearchInfo" site, the screenshot used is of Wikipedia. (You can even see the "About Wikipedia" link on the left).
Continuity mistake: During the scene where they encounter the beer truck in the alley, they are driving towards it, but in the next shot the car is the other way and are driving away from it.
Revealing mistake: When water is breaking through the wall you can see that at times the water is going through preformed squares.
Revealing mistake: In the scene where the barrels of beer are rolling off the truck, you can notice small squibs going off to make the barrels look like they have been shot.
Factual error: After Ben kidnaps the President he calls and tells Riley to meet him at the Library of Congress in twenty minutes. Traveling from Mount Vernon to the Library of Congress in ten minutes is NOT possible. Even in the middle of the night with no traffic it would take a MINIMUM of 30 minutes to make that trip.
Continuity mistake: Mitch Wilkinson jumps to a hanging ladder in the hidden chamber at Mount Rushmore, the first shot shows him hanging off the ladder with a pistol holster through his belt loops. The shot cuts away and when it returns there is no pistol holster where there was seconds earlier. (01:36:00)
Continuity mistake: Many beer kegs fall from the truck, yet the number remaining on the truck barely goes down from shot to shot.
Continuity mistake: During the car chase in London, the Range Rover with Mitch Wilkinson crashes into the rear end of the Fuller beer truck, damaging the left front bumper parts and headlights. Later in the chase, no damage is seen.
Continuity mistake: In the final scene of the movie, when Riley is walking toward his car, he walks approx 30 feet from behind the car up to the car, notice that there are no other cars behind him. As soon as he starts the car he accidentally goes in reverse and we hear him crash into another car, yet there was no one behind him for at least 30 feet. We did not see or hear another car pull in behind him in that few seconds. There is no car parked behind him.
Other mistake: There's a scene where they turn a wheel to control the flow of water into a much larger chamber. The cavern that is presumably completely filled with water (water is dripping off the ceiling) is massive. The flow from the smaller chamber into the cavern is relatively small. They enter moments after stopping the flow to find the cavern is drained. It should A) either take the cavern a very long time to drain or B) the cavern should never have been fully filled with water.
Plot hole: The idea that Ben Gates had to run away despite the President's being okay with the kidnapping does not make sense. The President could simply pardon him if necessary. However, when he ran away, he would likely be committing other crimes (fleeing and eluding police, reckless driving, etc.) that would not be federal crimes and so would not be pardonable.
Plot hole: When the characters are trying to escape Cibola through the central drain, the drain is actually, as Ben and Patrick imply, really just a room which dead ends, and they have to open the door to keep it from filling up. If this were the case, the entire city of Cibola and the room above (where Ben first says that all the water goes out somewhere) would have been completely filled up with water over the centuries. But in the movie the water had apparently been draining through that central "drain."