Robin Hood: Prince of Thieves - Robin Hood: Prince of Historical Inaccuracies.
I'm sure others will be adding to this list. Here are the ones I recall distinctly:
1) Ahzeem<sp> inventing the telescope about four hundred years early.
2) The use of the word "thug" about seven hundred years before the British would encounter the Thuggee cult.
Knowledge of history.
on 02-28-2000 and