When Trillian is first caught in the vault, Canton reads from a fax and says that she has six arrests and five convictions, while on the fax it shows 13 arrests and 11 convictions.

When the creature first strikes the ship, we see it attack from under the hull and towards the moving engine propellers. At this point in the film the engines, communication and emergency systems had been disabled by sabotage, hence the propellers should have been idle and not in full motion.

When they board the ship, Finnigan's boat is far below the cargo door; then, when he jumps from the boat in to help Trilian it is at the almost same level - which is plausible since the ship is sinking. However, when they jump on the Ski-Doo to escape, it is again far below the door again.

When Mason says, "I don't mean to sound like a pussy," he is pointing his rifle towards the water where our characters are about to dive in, but then in the next shot when he says, "but this shit is startin' to freak me out, man!" his rifle is pointing in the opposite direction.

Joey loses his rifle in the hallway but when he get to the boat and talks to Finnigan it is in his hand again, then missing when they get ready to escape.

Orchestating a sabotage as depicted in the movie is not possible, as modern ships have several on-board computers to prevent, precisely, the case of one of them going offline to cause the whole liner go blind. Furthermore, Maritime law requires every vital of the ship - particularly communications - to have officers on guard at all times, and although Canton owns the ship, he is still a civilian and would not have unlimited access to it.

The opening titles state that the South China sea is deep enough to swallow mountains. In fact the deepest part of the South China sea is so shallow that 108 of the world's tallest mountains would rise between 2000-3500 metres about the surface from the sea floor. Challenger deep, in the Mariana trench is several thousand kilometres east of the South China sea and it could easily swallow every mountain on earth in terms of depth.

When Hanover is being eaten by a monster, Joey hands him a pistol, a stainless steel semi-automatic. Hanover chooses to shoot at Joey one time before eventually attempting to turn the gun on himself before he is eaten, but the gun is now empty. The slide should have locked back after firing the last round, indicating that the gun is empty.

The motorboat travels at full speed at night, with the light in the wheelhouse on. In fact, the light in the wheelhouse should be kept off at night to improve visibility range.

During the attack scene, there are way too many people on the command bridge. Normally, even emergency situations aboard modern, large ocean liners, only require the captain, staff captain, communication officer and two lookouts. Also, the Argonautica seems to be equipped with sonar, which would be completely irrelevant for a cruise ship.

When Finnegan is using the pump shotgun, shells never come out the ejection port when it's cocked.

When Leila is welding the hole in the boat, the far away camera shot shows arc welding sparks while the close up shows a acetylene flame.

When the creatures first strike the boat, and the passengers are running scared, the young Asian woman locks herself in the bathroom. When the creature is sneaking up on her through the toilet that she is sitting on, she frantically grabs the sink faucet. When she first grabs hold of it, you can already see it moving before she pulls it off its hinges.

At least 2 characters say the ship is "sinking" but during the final escape scenes the vessel appears completely normal just as at the beginning.

When Trillian says "Not that anyone would notice." (in the elevator shaft) As she turns towards the camera she is mouthing something else.

When Trillian is caught trying to steal from the vault, the crew is reflected in the safety deposit box door as the guards bump it.

At about 7 minutes into the film during Canton's speech a crew member can be seen standing on the railing to his left.

When Finnegan realizes his boat is damaged beyond repairs, why did it not occur to him or any of the remaining cast to use one of the cruise ship's many lifeboats? The lifeboats would potentially be fully fueled, stocked with supplies to be stranded at sea for a number of days, contain communications gear, and they never would have needed the Sea Doo.

After the Argonautica is sabotaged, the man at the radar warns about something moving rapidly towards the ship and he is able to tell the speed and distance. Nevertheless, the same man claimed seconds before that they were sailing with "blank screens", and previously the imaging, navigational and communication systems are shown to be "disengaged". The radarman should not be able to detect the creatures coming because all instruments are down.

Their thousand round Chinese guns have no magazines and no ammo belts; therefore, they cannot shoot, let alone shoot 1000 rounds.