Factual error: When we see the Spanish newspaper reporting the death of Kane, the title says "el Sr. Kane se Murio". No self-respecting newspaper would omit the accent on "murió". Also, Kane was supposedly a worldwide household word, so he would never deserve "el Sr.". Finally, the colloquial "se" is out of place in a printed title such as this. The title should simply be "Murió Kane".
Factual error: In the opening credits, it says that the Knights Templar of Malta paid tribute to the King of Spain with the Falcon in 1539. The Knights that were in Malta were the Knights Hospitallers of the Order of St. John of Jerusalem. They mixed with the order of the Knights Templar, which went out of existence in 1314 and has also been founded in Jerusalem. They had nothing to do with Malta.
Factual error: All the light switches are the wrong way round for UK, where up is off. Presumably because film sets were in USA.
Factual error: Abbott and Costello have inadvertently enlisted in the Army but anyone weighing 240 pounds or more will be rejected. When Costello steps on the scale, the Army physician tells him, "You're in the Army. You made it by two ounces." Medical scales at that time (1941) showed weight in whole pounds only and did not show ounces.
Factual error: When the stork is flying to deliver Dumbo, the map shows the state of Kentucky above Alabama and Mississippi instead of Tennessee. (00:07:15)