Factual error: In circling over Washington Dulles, a plane would fly over several airports that they could land at with perfect communication, including Richmond, Baltimore, Andrews AFB, etc. Also, there is no communication from the airport to the plane but the plane would be in range of no fewer than 15 transmitting stations that could have relayed messages.
Factual error: During the opening credits, the show's copyright date is shown in Roman numerals as MCLXIV. In Arabic numbers, that's 1164 - it should have been MCMLXIV for 1964.
Factual error: No airport in NYC has the view of the New York City skyline that Kevin has when he realizes that his family is in Florida and he's in New York.
Factual error: When Kevin's mom leaves Paris to return home, the plane shown departing the airport is a DC-9. No airline uses this plane for trans-Atlantic service - it doesn't have the required range.
Suggested correction: Although not explicitly mentioned, it could be a connecting flight which departs the Europe from another airport. In this case, flying a short or medium range aircraft to reach a hub airport would be plausible.
In the case of this movie, that doesn't seem likely as it's highly improbable that the mother wouldn't notice that Kevin wasn't there at that time as she would naturally be checking on all her kids while waiting for the next flight. This does seem to be a movie error.
Factual error: Jonathan is lying in the middle of the skating rink when the second cashmere glove falls upon him. Looking around, he notices Sarah at the edge of the rink. Despite Sarah being a female and the fact that it is snowing, even Nolan Ryan would have a difficult time throwing something as light as cashmere that distance. (01:22:05)
Factual error: In the scene where Clark is working on the lights the full moon is shown. This is December 14th according to the advent calendar. On December 24th when Santa's sleigh goes sailing over the moon, it is still full.
Factual error: Finishing his rounds on the morning of Christmas Day, flying over downtown Chicago, the sun is over the horizon west of Chicago, Sunrises occur in the east, not the west. (00:26:10)
Factual error: When hero boy and girl and Billy are on the runaway car at the north pole, they crash into the stopper at the end of the tracks. They are flung backwards when in reality, due to inertia, they should have been flung forward into the guard rail.
Factual error: When Howard is running after the bouncy ball he is on the second floor of the Mall of America, however, you see him run through the LEGO store which is located on the lowest floor of the Mall of America, which is impossible if he was on the second floor before.
Factual error: Throughout the film, characters are able to break through on radio transmissions and speak to the other person talking, and the other person would hear them. In reality, they would have to wait until the first transmitter un-keyed the radio before any other discernable radio traffic could have be heard. (A good example of this is the scene where Ellis is giving up McClane.) (01:18:40)
Factual error: A very common error in First World War films. British soldiers were not permitted to shave their upper lips until 1916 - in 1914 almost all (unless physically unable to grow them) would have had moustaches.
Factual error: One of Angel's lyrics (in "Today For You, Tomorrow For Me) refers to the movie "Thelma and Louise." Rent (the movie) is set in 1989-90. "Thelma and Louise" was released in 1991. This was caused when they did the move from Broadway to the screen. The stage show did not specify the year. So when they adapted the stage show to the movie, they didn't check the references. Plus it just sounds cool. (00:28:25)
Factual error: Jack Lemmon cooks spaghetti for Xmas dinner. On New Years Eve he picks up the tennis racket, through which he had poured the spaghetti, and one piece hangs limp from the racket. It would of course, have long dried and be hard as before cooking.
Factual error: In the scene where Karen plays the album "Both Sides Now" by Joni Mitchell, she cries to the title track "Both Sides Now". A shot of the CD player indicates that track 7 on the album is playing, but "Both Sides Now" is track 12 on the actual album. (01:29:00)
Factual error: While travelling up the east coast from FL to ME they show a Santa Fe passenger train, which only runs out west.
Factual error: When Iris is unable to sleep she looks over at Amanda's bedside clock which displays 5:00 pm, however, moments later Iris discovers a button to lower the shade. There is bright sunlight coming into the room, however, in December the sun sets prior to this time (about 4:45pm according to timeanddate.com)
Factual error: On Day 3, look at The Embrey Star newspaper when it zooms into the headline. Above the headline is the newspaper's web address, hardly appropriate given the paper is from 1980.
Factual error: The movie was set in the mid-to-late 1940s, however, the red wagons shown in the display in Higbee's corner window at the beginning of the film, bear a Radio Flyer script logo which was designed in 1967. (00:03:10)
Factual error: In the drugstore scene where Mary whispers in George's bad ear, there are several shots showing a Coca-Cola thermometer on the wall where George hangs his jacket. This particular scene was to have taken place in 1919, but this particular thermometer wasn't produced until 1939.
Factual error: When Santa is shown the miniscule print on the 'Santa Clause' card (that he is supposed to be/get married) the Elf holds an enormous lens in front of it, to make it easier for Santa to read the print. From the distance Santa is standing at, from his point of view the card should appear upside down.