Factual error: There is a scene in which the Catholic high school boys are lined up to go to Confession to a priest. One of the minor characters is a compulsive masturbator, a recurring gag in the film. He is trying to estimate how many times he has wanked since his last Confession, and Kevin Dillon's character takes out a digital calculator to help him figure it out. The film is set in 1965, about 8 years before personal calculators hit the market. (I was precisely the age of the characters in 1965, and we would have sold our souls to the devil for such a device. It was still science fiction!).
Factual error: The movie takes place during or shortly before World War I. At one point, Quatermain and Jessie find a German base. Thus, they are probably in one of the pre-World War I German African colonies (Probably German East Africa or German South West Africa). There is a red, white, and blue French flag flying over the camp instead of a German flag.
Continuity mistake: When John Candy is woken up by his wife after getting drunk with Scully, he has a hoop earring in his right ear. Later during the regatta, the earring appears in his left.
Continuity mistake: The judge arrives and tells the audience that they can sit down. The guy on the left with a white linen shirt sits and crosses his left leg. Reverse shot, and he is repeating the action, this time crossing his right. (00:03:20)