Revealing: In the opening scene where Mariner is sailing his boat into the distance, land can quite clearly be seen on the horizon up ahead.

Revealing: When the Mariner hangs a man from a rope on his ship, the man jumps ahead a little: he puts his hand round his throat and makes strangled noises before the rope even goes straight.

Factual error: Regardless of the type of event that caused the ice caps to melt, Waterworld, as shown, is impossible because: A. Scientists have measured that if all landlocked ice (Antarctica, Greenland, and the like) melted, the worldwide water level would not rise by anywhere near enough to cover the whole world in water. B. The melting of the North Pole ice cap would have no effect at all on the worldwide water level because that ice cap is already floating in the water (try putting an ice cube in a glass of water and letting it melt. The water level won't change). C. Unless the event that caused the ice to melt also altered the earth's tilt, the poles would still be cold and would refreeze, lowering the water level.

Revealing: In most of the underwater shots you can see bubbles coming up from the cameraman.

Revealing: Right before the Smokers show up, you can see land on the left hand side of the screen.

Plot hole: How far ahead in the future are we anyway? Hundreds or maybe thousands of years? Do you know how long tankers like that can stay at sea? Twenty or thirty years at the most. That's a rather short time for everyone to forget about dry land.

Continuity: During the attack on the Atoll, a smoker on water skis falls over while going up the ramp. The next shot shows him hitting the wall of the Atoll, but he is now upright again.

Continuity: Near the end one of the balloon's ropes is shot, causing the girl to fall in the water. Yet, seconds later as they float off all 6 ropes are holding the basket up, uncut.

Continuity: After the mariner escapes and begins turning the gunboat towards the deacon, we see the firing path pass the end of the atoll wall. A couple shots later, it shows four smokers on jet skis getting shot as they exit the main gate, which is in the center of the wall facing the attack and had already been passed by the firing path.

Continuity: When the woman is on Mariner's boat, you can see that her dress strap is on her arm, but when the camera goes back to him and then back to her it is on her shoulder.

Continuity: In the beginning when Mariner goes diving off his boat for sunken treasure, he fills a timer with a handful of small stones which steadily drop to bring up the diving equipment when exhausted. After the camera shows some scenes to imply time going by, you can clearly see the amount of stones fallen is equal to about ten handfuls of stones.

Revealing: During the attack on the atoll, a smoker on a jet ski throws a flaming bottle of gasoline at the wall. The explosion occurs several feet from where the bottle hits the wall, obviously a pre-planted charge.

Factual error: The Exxon Valdez is designed to carry crude oil. Crude has to be refined into higher octane products to be used in jet skis, automobiles, etc. The refining process is difficult and requires large amounts of power. It would be impossible to do on the tanker itself. And it is extremely unlikely that the smokers would have come across high octane products on another ship. They tend to be refined near to their consumers and not shipped around.

Plot hole: When Costner spots the Smokers on their jet skis, his catamaran has no sails up and is dead in the water. He hastily puts up the sails and speeds away, outrunning the Smokers. This would be impossible in real life, from a standing start and light wind.

Continuity: When Mariner is knocked into the mud pit while in the cage we see that it does indeed sink. However as the woman and the girl are crossing the bridge to get to the windmill, the camera cuts to Mariner in the cage. The cage has sunk so that he only has room for his head and shoulders. Then as the woman and girl run past him there is another shot in which the cage is now further out of the mud and Mariner has room for the majority of his upper body.