Tanya informs Mrs. Quonsett that she'll be flying on Flight 103 to Los Angeles, and clearly knows the flight number from memory without having to look it up. A few minutes later when she hands Coakley the ticket she doesn't remember the flight number and has to read it from from the ticket.
In older releases, when the plane is shown flying out of and over the cloud cover, wires can be seen holding the aircraft up. The wires are not visible in the DVD version, except the first time the plane is shown flying up out of the cloud cover, when you can see the wires holding up the plane.
When Captain Demerest is reading off the plane's intended flight path to Rome, he refers to it passing over "Saint John, Newfoundland". The city in Newfoundland is actually called St. John's; Saint John is a city in nearby New Brunswick.
After the bomb detonates, Captain Demerest communicates with the cabin via interphone, but he's using the wrong microphone. The cabin interphone on the 707 looked like a telephone handset- he's using the radio mic.
When Mel and the girl are out in the station wagon, he wants to listen to the aircraft radio conversation. He asks for the frequency, and the dispatcher gives him and aeronautical frequency (in the 116 MHz range). The scene cuts to his car radio, which only covers from 150-174 MHz (police and public service). There is no way he could listen to the aircraft conversation on this radio.
There are two letters shown that are supposed to have originated in Chicago but have incorrect zip codes. The letter that Mrs Guerrero receives with the refund from the travel agent says "Chicago Illinois 20090", which would actually be in Washington DC. The other letter is the insurance policy that Mr Guerrero mails to his wife with a return address of "Chicago Illinois 62290", which would be in St Louis MO.
Mrs. Guerrero opens a letter with an enclosed refund check dated "Jan. 19 1970". The body of the letter begins, "In checking over our records of Tuesday, Janurary [sic] 16th...". In 1970, January 16th fell on a Friday, not a Tuesday.
At the end of the film when the hole in the aircraft is being examined, the thin, aluminum skin of the aircraft is splayed out like the petals of a flower. In actuality, the torn skin of the aircraft would be bent toward the back of the plane by the 500 mph wind blowing by.
When the nerdy kid remarks to Captain Demerest that he's seen a change in course because he sees different stars outside his window there is no possible way to observe stars from the interior of an aircraft unless it is totally dark. The movie aircraft is brightly lit within.
Capt. Benson, the pilot of the Boeing 707 that gets stuck just off the runway, says "You might tell your mechanic that I've got three million miles in the air". Pilots do not their state experience level as "...miles in the air". Rather, they state it as "...hours in the air". All pilots are required by the FAA to keep a record of their total flight hours in a personal Pilot Logbook.
Before the landing Capt. Demerest requests a PAR approach. The Air Traffic Control officer replies "Roger this will be a Precision Radar Approach..." which would have an acronym of PRA. However, PAR refers to Precision Approach Radar, the type of radar equipment used in the approach. The approach itself is commonly referred to as a "Precision Radar Approach" by pilots and controllers. Confusing, but the movie lines are accurate.
As the damaged 707 approaches the end of the runway Captain Harris calls for "right rudder". The 707 rudder pedals provide a low level of steering (though the steering tiller provides more) and the aerodynamic force on the still moving aircraft helps. In addition, stepping on the tips of the rudder pedals activates the wheel brakes on each side of the aircraft. Calling for "right rudder" was correct.
When Captain Demerest explains to the flight attendant that his copilot is required to wear an oxygen mask whenever the captain is absent from the flight deck, the flight attendant silently mouths his dialog as he speaks.
The explosive decompression would result in a rapid change in the relative humidity within the cabin, which would have caused water vapor in the air to cool and condense into fog. (Joe Patroni even pointed this would happen in an earlier scene when he describes what the bomb would do.) Nevertheless, there was no fog in the cabin following the explosion.
When the aircraft is seen flying out of the clouds from the outside, it is clearly rising nearly motionless among clouds of mist. In reality, the "clouds" would be moving quickly past the aircraft as it flew forward through and above them.
When Burt Lancaster is in Mobile One and says that he wants to listen in to the tower/aircraft radio transmissions, he's told to tune to 117.1, when he's shown tuning the in-car radio, he tunes to about 171.