Factual error: Robin and Azeem land at the white cliffs and Robin says something like, 'Tonight we will dine with my father'. Those white cliffs are the Seven Sisters in East Sussex, about 200 miles from Nottingham. It would probably take about two weeks to walk it. They also reach Hadrian's Wall in the next scene, which is 200 miles further north than Nottingham.
Factual error: Deer are not repelled by the smell of human urine, and in fact it does not have "a" smell - it has many. The smell of human urine varies enormously based upon diet, health and environmental factors so that no wild animal could possibly be scared of them all. Even if Lou didn't know this (and everything about her character suggests she should), Doctor Stone would - he is a doctor, after all.
Factual error: In one scene, Vada is showing off her mood ring. The movie is set in 1972 and mood rings were not created until 1975.
Factual error: There's a scene where Belle's father is riding away in the snow on his horse - the tracks left behind by the horse are exactly backwards. The round part of a horseshoe is at the front, not the back. (This was a deliberate 'in joke' done by the animators.)
Factual error: When Mike is in Idaho he has a clear view of Mt. Hood. Even if it were possible to see the mountain from so far away (over 200 miles), there is another mountain range lying between Idaho and Mt. Hood, blocking the view.
Factual error: There are numerous references made to the Finnish Royal Family, and they even make an appearance. Only problem is, Finland doesn't have a Royal Family.
Factual error: Garfield plays a violin in the film. The miniature displayed on the desk is supposed to be a violin, but it is actually a cello on its side.
Factual error: While the movie is set in 1957, photos of Elvis attached to a wall were taken in the mid 1960s. The orange shirt shot is from Girl Happy, 1965 and the black and white shot below it is from Roustabout, 1964.