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: Mel and Goldie board a ferry. A visible sign states 'Detroit-Racine Ferry'. Detroit is on the east side of the state of Michigan but Racine, Wisconsin is west of Michigan, across Lake Michigan. The only water route to get from Detroit to Racine would be to circumnavigate the entire state of Michigan.
Factual error: When the USS Dallas submerges to attack the Red October, they rig for battle stations as well as rig for red. On a submarine, rig for red is only for periscope depth operations at night, to allow control room watchstanders eyes to adjust to the darkness topside. No other area on the boat rigs for red. Throughout the movie the lights darken along with battle stations. No naval ship would reduce visibility on purpose in a heightened state. (01:31:00)
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.
Factual error: Though extremely modest on today's standards, the dress worn by Clara to the hoedown shows far too much cleavage for the time. No schoolteacher would ever wear a dress like that in the 1880s.
Factual error: In the scene at Idlewild airport, the actors walk past the rear of an easily identified 1965 Chevy Impala. Occasionally Chevrolet introduced vehicles early, but never two years early.
Factual error: Cher complains that Astroturf is going to ruin baseball. Mermaids is set in 1963 when Astroturf was still being developed under the name Chemigrass. It wasn't christened Astroturf until it made its world debut on the floor of the Houston Astrodome in 1966.
Factual error: They hold a huge dance in the hangar at night, and Dennis leaves to walk to the Memphis Belle through the hangar doors, which are wide open. The whole flight line, tarmac and hangar are bathed with light - on a US Air Force base in East Anglia during the blackout. Blackout restrictions were rigidly enforced and were not eased until September 1944. The last mission of the Memphis Belle was in May 1943.
Factual error: One of the first races that Cole runs is Phoenix. Phoenix International Raceway is a very flat track. There are several shots in that segment showing a high-banked oval.
Factual error: One of the brain surgeons says about Cain's brain, "it's nice and clean in here, there's no damage", except we see throughout the film Cain using the drug Nuke, even a new variation of it called Blue Velvet. When he injects it he's with his chemist Frank, and mentions two of its ingredients, "benzadrine and scopolamine" - no way his brain would be nice and clean.
Factual error: The movie is set in the late 60's. In the restaurant scene two guys on stage are singing "A Horse With No Name" which didn't come out until 1971.
Factual error: Asystole (the lack of cardiac activity, also known as the 'flatline') is not treated with defibrillation (electric shocks) but with alternating doses of the drugs epinephrine and atropine.
Factual error: When the Security Guard in the pump room gets bitten on the nose, he starts shooting with his revolver (a SIX shooter). Count the bangs. He manages to fire SEVEN times. (00:39:45)
Factual error: Throughout the entire film Burt holds all of his rifles' butts underneath his armpit, rather than against his shoulder. A trained "survivalist" such as him would surely know better. Holding the "elephant gun" in such a way would most likely break his arm, wrist and hand when it fired. (00:58:20)
Factual error: After Robert De Niro awakens, Robin Williams takes him on a ride around New York and Robert is amazed by all the surroundings. The movie is set in the early 1970s, but you can see plenty of vehicles around from the time that the movie was filmed (1990). Notice the square headlights that originally appeared in the late 70's.
Factual error: The Henry Repeating Rifle seen in 1865 is impossible, because it's the "King's Patent Henry Rifle" which wasn't out until 1866. The original Henry had a loading tube under the barrel, not one on the side of the breech. Plus the ammo used is the larger, more modern rounds.
Factual error: During the scene where Peyton is hanging from the helicopter, Durant is firing at him with a grenade-launcher. He hits several cars, most of which end up in flaming wrecks. Despite this, traffic continues as normal... If you saw cars around you exploding, would you casually continue on, oblivious? This error is especially visible with the truck driver, whom reacts to Peyton landing on top of his truck, but seems oblivious to the chaos behind him.