Factual error: Dorothy tells Miss One that she lives at "433 Prospect Place." Dorothy is supposed to live in Harlem. Any New Yorker knows that there is no Prospect Place in Harlem. In reality, Prospect Place is in Brooklyn and is, in fact, where the street scenes for "Harlem" were filmed.
Factual error: Jake takes a huge piece of gold and condenses it down into a small strip. It is then lifted with no difficulty. For the science of the film to work, this would have to be done without losing any of the gold's mass, or they could just get a small piece. As of such, the condensed gold would be just as heavy, if not heavier than in its original form.
Factual error: It was mentioned the museum has $3 million in gold bars. At 1978 prices, that is about 280 pounds. Gold is fairly heavy and the size of the bar shown in the film looks like 25 pounds. Assuming about 25 pounds per bar, I counted 134 bars or 3,350 pounds or almost $36 million dollars. I guess a big stack of gold bar looks better than a small stack of 11 bars. (00:41:55)
Factual error: In the 1953 sequence when the headmaster is driving Fiona and Paul home, the yellow car parked in the road is a Vauxhall Viva HC, which didn't start production until 1970.