Factual error: In the scene near the end of the film where Victor Buono is sitting in his chamber addressing his two captives, he opens a can labeled egg foo young with a can opener. He pours the liquid contents into a bowl. Egg foo young is an omelet and could not have passed through the small holes made with a can opener.
Factual error: The British carry WW-I, No 1 Lee-Enfields, and the Germans carry WW-II era British No. 4 Lee-Enfields.
Factual error: At the end, during the master wide shot of Diana and Shandor (C19 characters) standing over the castle moat, there is a modern aeroplane's vapour trail high above their heads.
Factual error: In the scene where Lee Marvin states that Burt Lancaster loves explosions, Burt Lancaster makes a remark about the big bang theory. He says: the whole universe started with a big explosion. The film is set in 1917 which is 10 years before Georges Lemaître launched the big bang theory.
Factual error: Racer Dave Owens goes down to an unspecified Southern state to race and becomes a moonshine runner. However, the Dodge he drives in his illicit activities possesses California plates, as does the Plymouth driven by the IRS agents.
Factual error: When Tuco is in the gunshop messing around with the guns, one gun has the cylinder and barrel moving back and forth by manipulating the trigger guard-lever. This is a Belgian Galand & Somerville revolver, a gun that did not exist until 1868. This film takes place during the US Civil War, which ended in 1865.
Factual error: The Dalek mine is set in Bedfordshire. We see the encampment with high mountains beyond. Bedfordshire is a county of low rolling hills, with virtually no rock.
Factual error: When Mother Superior announces those girls who wish to stay and join the convent, she states they will join the Novitiate. Actually, not correct. Their 1st step is called Aspirancy / Pre-Candidacy Then Postulancy / Candidacy THEN they are a Novice, for a few years, before taking Final Vows to be a Full Nun.
Factual error: Alva and Owen go see the movie "One Way Passage", released in October 1932. The movie takes places in August, the year is not stated explicitly, but there's a wall calendar in the dining room at the boarding house (you can see it when Legate leaves, calling himself a fink) for 1934, and at the same time the date shown in the office (when Redford sits at the desk to decide who will get pink slips) is August 14, Friday, which would set the movie in 1931.
Factual error: The onlookers are eating pears in spring. Wrong time of the year for ripe pears.