Snakes on a Plane (2006) - 2 major mistakes

Plot hole: The snakes are contained in the cargo hold which is shown to be unpressurised on this aircraft (there is an altimeter which releases the snakes after it hits 35000 feet - if the hold was pressurised it would level off at cabin pressure, which is about 8,000 feet). A cargo door is left open to allow the snakes into the passenger compartment, but this would either cause the plane to not pressurise properly, causing everyone on board severe breathing problems if not worse, or would keep the hold at cabin pressure, meaning the altimeter would never reach the right level to release the snakes.

Factual error: One of the subplots involves a young boy ("Tommy") who is bitten by a cobra and the attempts to save his life. When they are working on his arm, it is horribly swollen & filled with fluid which they drain by cutting open his arm. Cobras secrete a neurotoxic venom which attacks the nervous system. It would not cause noticeable swelling at the bite site. The symptoms Tommy has would indicate a bite from a snake which secretes a hemotoxic venom (such as a rattlesnake), which attacks the blood stream & tissues, causing swelling.