When the plane hits the derrick of the oil rig, there is no damage to the wing in the very next shot.
When the captain is being rescued, the actors in the zodiac change after they pick him up. The first pair are both dark haired and have facial hair, while one has his shirt off. When they return to the ship with Gallagher (Jack Lemmon), they're both blonde, clean-shaven and wearing shirts.
After the sea rescue, passengers' clothing has dried once aboard the rescue ship. While it might not make sense for the clothing to have dried, few of the passengers' hair was ever wet in the first place, as they walked out the emergency exit directly onto the wing and were transferred into zodiacs.
After hitting the offshore oil rig, the outer starboard engine (#4) is shown failing and taking fire. However, in the cockpit, Engine #3 (inner starboard engine) is shown failing with a skyrocketing EGT indicator (exhaust gas temperature), yet Engine #4's fuel cut-off and fire extinguishers are operated by the pilot.
When Capt. Gallagher is explaining the need to get the raft to the surface to the group on the plane, he explains that it is designed automatically to trigger its SOS beacon when it reaches the surface. After Gallagher hauls himself aboard the raft, however, the first thing he does is extend the antenna and switch on the beacon.
The sleeping gas canister shows "CR-7". CR is actually a tear gas, not a sleeping gas agent.
During take off, a large number of loose items (including a huge fruit buffet set up on a table) are laying about in a way that would be totally unacceptable for any airline. Even after the ditching/crash, the bowl of grapes is sitting proudly and undisturbed on its table!
A Boeing 747-200 would not sink if the main cabin was intact. The main cabin would provide about 1,300,000 pounds of buoyancy against a maximum gross weight of about 800,000 pounds. Further, the plane would be equipped with life rafts for the crew to deploy.
During the first landing, the engine instruments are pointing in random directions; in real life each horizontal line of gauges would show roughly the same reading. The needles don't move when Capt. Gallagher closes the throttles or engages the thrust reversers.
Any pilot can turn off the plane's transponder, thus making it impossible for ATC to track the plane. There would have been no need to descend below radar. Of course, not descending would have taken away the cause of the plane to crash.
After submerging in the Atlantic, the captain said the airplane is "Pressurized". While some might think otherwise, it is possible for a submerged plane could retain air for a period of time. It should be noted that when at altitude, a pressurized airliner maintains internal air pressure that is considerably higher than the outside air. When underwater, the situation is reversed. Because of this, even a perfectly intact airliner would certainly have leaks. As the plane in this situation is only perhaps 100 feet below the surface, the water pressure is 44 pounds per square inch. At cruising altitude the internal pressure is maintained at about 12 pounds per square inch, with is equal to an altitude of 6,000 feet.
Gallagher is shown swimming upwards without inflating his life vest. He was out of air, which means that he is either trying to pace himself due to compression issues or that it didn't occur to him to inflate his life vest.
When the plane is taking off you can see the logo of the airline used in Airport 1975 on the tail of the plane. Columbia Airlines.
When Gallagher and Buchek are exiting the rear cargo door of the aircraft (while it's being loaded in the hangar), the "American Airlines" logo on the 747 is clearly visible on the rear vertical stabilizer.
Just before one of the hijackers hits the on-flight security guard on the back of the head, you can see the actor playing the security guard flinch before he is actually hit on the head.
At about 1:01:43, when they are bringing the injured bartender into the bar area, the shadow of the camera can be briefly seen on Joe Cotton and Gill Girard's back.
While some might think that the 747 does not have emergency doors over the wings, this is incorrect. there is a door towards the back of the wing on either side. It allows passengers to walk onto the wing if necessary but the exit slides go over the trailing edge of the wing with slides that parallel the fuselage.
When the search and rescue plane flies over the crash site the aircraft is spotted on flat sand. In scenes before and after this the aircraft is on the edge of a trench ready to slide over.
At one point, when the aircraft is on the bottom and not moving, the massive entertainment center simply falls over. An item such as this would not be so massive, as this would be impractical. In addition, this item would have been solidly anchored to that it could withstand anything, including most crashes, without falling.
When questioning the copilot, Captain Gallagher doesn't ask the obvious question, which is about the cause of the crash. This omission is unrealistic. If he'd known that the plane had clipped the derrick of an offshore rig, this would have meant that there was a fix on the location and direction of travel. By not asking this question, Gallagher was being wildly incompetent.
If the chronology demonstrated throughout the film is correct, the life raft would not make it to the surface until after sunrise, or sometime between 7:00 a.m. and 8:00 a.m. This would make it approximately nine to ten hours after the crash. Given the activities seen in the film, this would mean that they would have spent at least six hours doing nothing before starting to figure out the solution. This time can be tracked by the backlit daylight on the wall of the lounge, which has a scrolling plastic map with the lighting indicating the areas of daylight and darkness. When the doctor goes to check on the piano player, which is about twenty minutes after the crash, the map shows it to be noon in central Australia. This would make it about 10:00 p.m. local time.
When the plane is about to crash into the sea, the shots from the cockpit show the plane heading nose first towards the sea. The outside shots show the plane flying almost horizontal and only a few feet above the sea. The plane would have to be flying in almost a sine wave trajectory to repeatedly be heading straight for the sea.
It would seem that an operating oil rig would report a airplane striking their tower.
Numerous Naval units shown as well as their hangars bear unit numbers for units located at NAS North Island in San Diego. The film is set in Florida.