Unfortunately, for a movie claiming "historical accuracy" around Richard and John, it was far off the mark. If I had the desire, I could watch it again and pick out all of the things that were inaccurate. From what I remember, though, there was almost a serious lack of understanding of what "England" was in the Norman period. One has to remember that William I (the Conqueror) was the Duke of Normandy. You'll remember that as the place in France that the Allies invaded in World War II. Richard and John still owned that tract of land and, when Henry II married Eleanor of Aquitaine (and her huge tracts of land - sorry, it had to be said), they acquired even more of what is modern-day France. The French King, Phillip, on the other hand, pretty much owned Paris and nothing else. His dukes and barons were only partially supportive of him and only when it suited them. The king of France was a (feudally) weak king indeed. There is sequence in the movie where the French invade England - across the English Channel. Which they wouldn't have needed to do - they just could of walked north to Normandy and invaded there. Not as dramatic, no, but it showed a pretty poor grasp of the European map of the day.
The second thing was that everyone spoke English, even Richard and John. Who most certainly didn't - they spoke Norman French (see my first post). There's a scene where Richard is walking among his troops (Henry V anyone?) and meets Robin Longstride - and they have a lengthy exchange. Which they couldn't have because Robin didn't speak French and Richard didn't speak any version of English (that we know). There's even another scene where Phillip II asks a vassal to speak English to him. *facepalm*
Overall, the movie is fun, but don't look at it for historicity. Quite a few of the things in the movie are just plain wrong (some I pointed out above) and I think much was done for moviegoers' tastes as opposed to accuracy (the invasion of the British coast, for instance). Robin Hood is one of those interesting pieces of medieval history that's carried forward to the modern era. Original Robin Hood ballads were entertainment with occasional fable-like morals. Only later (around the 16th century) did the "evil Prince John" enter the picture - most of the ballads before then were just about Robin and his men being likable outlaws. This movie, while engaging and telling a good ripping yarn, is moving the pendulum back toward history - just not quite far enough.***
* Why no Brits play Robin Hood in major movies I'll never know.
** There's no real evidence that Richard and Phillip were lovers, but oh, if they had been...
*** I don't think American movie audiences can handle the truth (with a tip o' the hat to Jack).****
**** You'll notice I backed off using NB for footnotes. I've just decided that I like the *'s better.