Deliberate mistake: I know this has been disregarded for the fun effect, but gasoline motors require air to work. When Edgar drives his tricycle into the river while being chased by Napoleon and Lafayette, it should have stalled and stopped working.
Deliberate mistake: The German tanks in this movie are not really Tiger tanks. They are Russian T-34's made to look like Tigers. The T-34's are done up very realistically, including Zimmerit (the wavy pattern on the hull of the tiger), which was an anti-magnetic paste put on the tank.