On departure from Honolulu the DC-4 has unpainted propeller blades, but on arrival at San Franciso, the propeller tips are painted red and yellow (an apparent safety measure to let ground crew see rotating propellers before walking into them).
When Dan Roman stumbles from the burning wreckage of an airliner in a flashback sequence, he sees and reaches for a burning teddy bear. When he picks it up, it's no longer burning.
At approx. time index 1:32, of Mr. Briscoe is helped into a life jacket by the stewardess. Later, at approx. the 2:06 mark she comes by and he's not wearing it. She asks him to put it on. Given the difficulty of the character's mobility and needing help with such a task, it does not seem likely that he took it off himself in the interim. Nor is it likely that Ms. Chen would have helped him if he had asked, or sat by quietly if he had managed to take it off himself the first time.
Near the end of the film, Air Traffic Control clears the aircraft to land on "runway 39" This is impossible. Runways are numbered are within 10 degrees of their actual magnetic heading, and since there are only 360 degrees on the compass, the highest runway number possible is "runway 36".
Passengers were instructed to inflate their life vests when, in reality, if the plane goes down in the water, this would cause you to get pinned to the ceiling of the plane & nearly impossible to maneuver & get out . A person should wait until they can swim out of a submerged plane & then inflate the vest.
Hawaii was a U.S. territory at the time, so no one would have to go through immigration for a flight from Honolulu to San Francisco, even those who were not U.S. citizens.
On the departure runway, Johm Wayne transmits "420 ready for take-off" and the plane immediately starts to roll, without waiting for the mandatory takeoff clearance from the tower.
The four cockpit crew members are all wearing headsets and do not have the overhead cockpit speakers on. During the entire movie, you never hear air traffic control talking to the crew. That would apply here, too.
When stewardess Spalding was preparing the liquor drinks, a problem with the plane caused a severe vibration. The table and the drinks shook, jumped and nearly fell, yet she did not shake, nor did the walls, or the curtain right behind her.
The sound of the yellow flying bomb is wrong. It is audibly a jet engine, but the flying bomb is actually a German V1 which is powered by a pulsejet: slats on the nacelle let in air that is mixed with fuel and ignited by a spark plug, forcing the slats immediately closed. Power is thus delivered in rapid pulses such that the motor makes a rapid dull buzzing noise.
In the flashback story her husband tells, Clara Joseph falls down some stairs and kicks a waiter's tray in the process. However, when they cut from the closeup of her feet, she is obviously sitting on the bottom step. She then leans back, takes aim, and kicks the tray. She then lies back like it was all one continuous motion.
The Coast Guard B-17 that intercepts the airliner is never heard from again. It would have been invaluable in advising the airliner's flight crew during the approach to San Francisco.
The navigator says he confused knots and miles. Knots are a measure of speed (one nautical mile per hour). He means he confused statute miles and nautical miles--a. nautical mile is about 1.15 statute miles.
At the missile testing site, the word "missile" is misspelled "missle" on the sign.
The flight engineer and the stewardess never put on life jackets even though everyone else on the plane had done so.
In the final scene, Garfield is smoking a cigar around the plane, despite the signs indicating smoking is only permitted inside the canopy and the fact that he works at the airport.
The stewardess inflated the little boy's life jacket by blowing into it, in order not to disturb him. But if he had then pulled the red handles, the life jacket would have burst. You should only use the mouthpiece if the auto-inflate fails, or for a top-up.