Factual error: After the plane is submerged, Jack Lemmon says, "... this plane is pressurized!" Jet aircraft are pressurized by bleeding air from the compressor sections of the engines into the cabin; in other words, the plane is only pressurized while the engines are running. Also, aircraft are only pressurized to a few psi above the outside air pressure at altitude, and never to more than the air pressure at sea level. The water pressure would be a great deal higher than the air pressure in the cabin, and since aircraft are not water tight, the water would quickly fill the aircraft. (If the aircraft was in 50 feet of water, the water pressure would be 21.7 psi, versus a maximum cabin pressure of 14.7 psi.)
Factual error: In the many shots of the plane underwater, both from outside and looking out from within, the "sea" resembles the bottom of a swimming pool more than the bottom of a shallow area of ocean, as not a single fish or any other aquatic life (which would be abundant in areas around The Bahamas) is ever seen.
Factual error: In the opening credits, the plane is showing landing over the Capitol Building on the way to Dulles. Dulles is no where near the Capitol Building.
Factual error: The function of the US Navy in this movie in being called to raise an intact aircraft is plausible. Their actual role is usually to do with raising submarines. That being said, what isn't plausible is for a 747 to be heavy enough to cause equipment such as strapping to snap and fail, when a submarine is so many magnitudes heavier. A fully laden 747 can be over 400 tonnes, a moderate Los Angeles class submarine is over 6000 tonnes.
Factual error: Whilst the use of air-filled balloons is entirely credible when raising something like a 747, the air balloons would not lift the aircraft out of the water. The balloons would go as high as the ocean surface and no higher, meaning the access doors to escape the aircraft would still be submerged.
