Factual error: When True Heart skydives down to Earth, she is wearing goggles with a wraparound strap. She takes these off and drops them in her backpack where Baby Swift Heart is hiding. When he pops up a split second later wearing the goggles, the strap is under his bonnet.
Factual error: When Fievel is being dressed by the pigeon there are two American flags in the background. The flags have too many stars for the mid 1880s, when the movie is set.
Factual error: The aircraft are definitely post-WWI. Biggles is flying a De Havilland Tiger Moth, which appeared in 1930s. The German fighter is probably the PT-23 Stearman.
Factual error: After Miyagi and the kid have the conversation with the military man they drive off and round a corner. A scene is shown of the sea and very visible is a shot of "Chinaman's Hat" Island. A feature that if you have ever been to Oahu, Hawaii near Kualoa Point you would know is on the island of Oahu and not in Okinawa where the movie is supposed to take place. See Chinaman's hat at this site: http://www.hawaiiweb.com/oahu/sites_to_see/chinamans_hat.htm.
Factual error: When the alien craft speeds away from the NASA base, its slipstream tears off the roof of a small booth. But the wake also should sweep the people in its flight path down to the ground; it is too close for that not to happen.
Factual error: When Number 5 is watching Saturday Night Fever, he is watching and grooving to the climactic dance-off scene in Saturday Night Fever on TV. Stephanie then enters and the scene on TV shifts to one much earlier in the movie he's supposedly watching. (00:57:15 - 00:59:30)
Factual error: Apparently, Ratigan had to cross the River Thames to reach Big Ben from Buckingham Palace as evidenced by him tossing Fidget into the river before taking reign of the blimp. However, the two landmarks are on the same side of the river.
Suggested correction: Ratigan changed direction multiple times during the chase because he was trying to get away from Basil. He may have flown away from that side of the river, but then after changing direction he flew across to the side he came from again.