Factual error: The narrator near the beginning says Al Capone was born in Italy. He was actually born in Brooklyn NY.
Continuity mistake: As Steve and Mike are leaving in the police car, Mike turns and puts his arm back as he looks back to start driving in reverse as Steve waves to his wife. It cuts to an angle from behind his wife as Steve puts his arm down, but then Mike turns and looks back again a second time in this shot to start backing up. (00:20:35)
Character mistake: Wilhelm Keitel was a field marshal, not an admiral as stated during the sentencing.
Revealing mistake: Back at his NAACP homebase, Marshall meets with the boss who is already sending him to deal with another case. In the close-up of the newspaper he's reading, check out between the actor's fingers. You can tell that half of the article, which begins in English, suddenly switches into Latin 'lorem ipsum' filler text. (00:06:20)
Factual error: The movie is set in Philadelphia, but the bus at the beginning crashes at a crossroad in front of the fast food joint Admiral Submarine, a recognizable location in Brantford, Ontario, where the movie was shot. (00:05:00)
Continuity mistake: Byron walks towards the maid and surrounds her waist with his arm. From the angle behind, he is repeating all previous movements.
Continuity mistake: Juliet is on the bed with little girl Kit. The child has a ribbon is her hair then looks up at Juliet and it becomes a slide. Next cut it is a ribbon, then a slide. Then the girl sleeps on Juliet with just a ribbon visible. (01:19:00 - 01:20:00)
Factual error: About 20 minutes in, the group find a Welsh miners' group in the phone book. The character who is making the call speaks the first two digits of the phone number: "0, 1,..." The movie is set in 1984, when the dialling code for that district was "0639" In that year, "01" was the code for London, not Wales.
Continuity mistake: After Rita and Eddie's fridge is repossessed they are arguing outside their flat. On the wall outside their neighbours' flat there is a wheeled trolley or pushchair hanging on the wall. This disappears and then reappears several times during this sequence of the film.
Factual error: The telephone for the phone bank doesn't have a phone jack cord connected into the back of the telephone. (01:15:14)
Continuity mistake: When Ahmed Alhaznawi (the tallest of the four terrorists) has just gotten through the metal detector, a pattern of light appears on the floor behind him between shots.
Factual error: During the film, there are extracts of two songs - 'The Spy' and 'Maggie McGill' - from the Doors' fifth album, Morrison Hotel. Great songs, however the film is set in 1968 and Morrison Hotel was not released until 1970.
Continuity mistake: At the beginning of the film when Georgiana is talking with her mother about her engagement, the curl running down the back of Georgiana's neck disappears and reappears multiple times.
Visible crew/equipment: When Helene Hanfstaengl says to her maid, "I'll speak to you in the morning," she stands on a cue mark in yellow tape.
Factual error: At a very early point in the film, the King says something along the lines of "....and these are your playmates". In the background is a horde of 17th century ladies boating on the Achille Duchenne water parterre at Blenheim Palace. The palace wasn't built until the late 18th century, and the parterre was not designed until 1925.
Factual error: During their transatlantic boat trip, on their way to Athens, the American athletes are having fun naming various foods from back home that they already miss. One of them claims he misses chocolate chip cookies. Oops. That particular cookie didn't exist until Ruth Wakefield invented it in 1930.
Factual error: The weapons for this film, save for the American Krag-Jorgensen rifles, British Lee-Enfield MLE rifles, and German Mauser Gewehr 98 rifles, are completely wrong. The Russians, who had Mosin-Nagants, are portrayed with Mausers. The French are for the most part correctly poratrayed with Lebel Mle. 1886/93 rifles, but a few have Berthier rifles that weren't used until 1907. The Austro-Hungarians are portrayed with a mixture of Mausers and Berthiers when they would have had Mannlicher M88/90's or perhaps Mannlicher M95's. The Japanese are equipped with Mausers and would in reality have had Muratas. The Italians have a mix of Berthiers and Mausers, but would've used Vetterli-Vitali rifles. The Chinese Imperial troops and Boxers both have Gewehr 98 Mausers. Although they did indeed have Mausers, they had the far earlier Gewehr 71's and Gewehr 71/84's.
Factual error: The attack on the OPEC meeting in Vienna takes place on December 21. Yet, when Carlos' team exits the tram, the trees are full with green summer leaves and the sun shines as it would on a high summer day.
Factual error: In this scene several sailors attack Alice Paul and tear down the demonstrator's banners. The older sailor's petty officer rank specialty insignia featuring three lightning bolts, Radioman, was not created until 1921, four years after this incident. (01:30:35)
Factual error: The system devised to get the height right was, in the film, said to have been thought of by the 617 Sqn crews following a visit to the theater. In reality it was devised by the 'boffins' at Farnborough.
Suggested correction: See many previously posted 'mistakes' of this type and the standard correction: this is not a documentary and never pretended to be. It is a war drama and many facts were changed to fit the action.
Those correction are often made in fallacy. Dramas based on historical accounts have liberty to change small or inconsequential things, like adding a person that may have never existed, or change a relationship for dramatic purposes. Despite not being a documentary, unless it's a fantasy film, changes in historical facts are mistakes (for example, a drama can't have the Eiffel Tower in London just because it's not a documentary).
Suggested correction: This was the version given in Brickhill's book. The real story wasn't published till many years after the film was made.