The color scheme of Flight 502 changes several times throughout the movie.
When the plane lands in London, the sky is shown at dawn, yet when the plane finishes its taxiing, it is night. Given the time-frame of the movie, the flight should be landing in the morning.
Flight 502 is cleared to take-off from "runway 90" at Kennedy Airport. Not only does Kennedy Airport not have such a runway, but it would not exist in real life, as runways are numbered according to heading in tens of degrees (1 to 36).
Flight 502 is an overnight flight to London, yet no one is shown sleeping and the lights in the First Class cabin remain brightly lit throughout the flight. (Only one character, Millard Kensington, is actually shown receiving a pillow and blanket).
The passengers are supposedly sitting in the First Class lounge at JFK, although the Theme Building at LAX is clearly visible in the background.
Danny Bonaduce's character, Millard Kensington, disappears from the first class cabin about halfway through the movie, never to be seen again.
Members of the crew repeatedly reference the airplane cruising at 38,000 feet. Eastbound routes, such as the New York to London route depicted, are always at odd numbered thousands of feet. An aircraft cruising at 38,000 feet would be westbound.