Factual error: Towards the end when the cavalry uncovers the American flag, it has 50 stars.
Factual error: Maleficent states that Princess Aurora will prick her finger on a spindle - the part of a spinning wheel that holds the bobbin. Spindles aren't sharp; what Aurora actually pricks her finger on is the distaff, which is used to hold the fiber before it is spun.
Factual error: When Cary Grant is attacked by the crop duster, he is supposed to be between Chicago and Indianapolis. Unfortunately, northwest Indiana looks nothing like this. The scene in the movie has miles and miles of treeless landscape. Even in the flattest farmlands of Indiana, there are many visible groves of trees.
Factual error: The galley during the battle scene is rowed by slaves. Romans during this time period didn't use slaves to row their galleys. Rowers had to be able fight. If not, the Romans would be outnumbered 200 to 30 when they boarded the pirate ship as the pirates rowers would be able to fight.
Factual error: Iceland sure looks a lot like the California desert.
Factual error: As Frederick is explaining to his guests how to use their .45 automatics, he fires one round at a near-by vase, shattering it. However, it leaves no bullet hole in the wall directly behind the vase.
Factual error: In the shot where the female band members run from their hotel (in Florida) to the beach, mountains can be seen in the background.
Factual error: Anne Frank received her diary on her birthday, and started writing on it 1 month before she went into hiding. In the movie however, she is presented with the diary on the first she arrives at the hiding place.
Suggested correction: Since this movie is based on actual events and not considered a documentary, then the film-makers are allowed to change things to their liking.
While I feel like this sort-of correction could apply to certain elements of movies based on true stories like dramatized scenes (since there has to be some condensation of time and some elements boosted for drama, which can be chalked up to filmmakers changing things), I think a film based on a true story contradicting a known hard fact like this should 100% count as a mistake. Otherwise, you could just as easily argue that any factual error in any film is invalid because the filmmakers are "allowed to change it."
Factual error: The movie is set in Cardiff but the Transporter Bridge seen at the beginning of the film is really in Newport.
Factual error: When the military are going to attack the flying saucers in Washington D.C., there's some shots where you can see trucks and airplanes in a deserted region. Washington is hundreds of kilometers away from the desert. (00:18:30 - 00:21:10)
Factual error: The USS Sawfish is supposedly a nuclear powered submarine, but the shots of her entering Williamstown show diesel exhaust coming from her. (Apparently they had to substitute an Australian diesel-electric submarine).
Factual error: Atop the desk in the Captain's stateroom is a model of a 5"/25 wet mount gun. The 5"/25 was designed for, and mounted on, U.S submarines; however, it was not introduced into service until 1944, and this is set at the start of World War 2.
Factual error: The movie takes place "somewhere in the South Pacific, 1942", yet the transport plane taking LTJG Braden to Hawaii has post-war markings.
Factual error: In the scene where we see a DC-3 making a air drop over the jungles of "Burma" they fly over the ancient city of Sigiriya (a mountain fortress built around 473AD) which is actually in the country of Sri Lanka.
Factual error: After taking Jan home, Rex Stetson/Brad Allen goes back to his apartment and calls Jan. Since they share a party line this would be impossible because a party line is a single phone line shared by two people. For Brad to call Jan he would have to call his own phone number and would receive an engaged/busy signal. (00:41:07)
Suggested correction: Brad Allen explains to Jen that they have a code number for their party line. It is 793. She can call him, and he can call her by dialling 793. No need to dial his own number.
Factual error: Karnak was an Egyptian city, not one of their gods.
Factual error: The Maxim guns are mounted on Mk IV tripods, not introduced until 1906 (plus with direction dials fitted, which didn't get introduced until 1915), and metal ammunition boxes are used with them (again introduced in 1915 - they should be wooden at this date).
Factual error: When Mrs. Lane screams at the sight of the horse, on the back of Karen Steele you can see the outline of a modern bra under the shirt. (00:23:30)
Factual error: It appeared that, during the engagement with the Serapis, every hit by either ship's guns resulted in an explosion and fire. Unfortunately, explosive shells wouldn't be used on shipboard (aside from bomb vessels) until the next century.