Goofs

After Modred 'dies' his torso clearly shows continued breathing.

At the end of the fight between Arthur and Lancelot, Lancelot breaks his sword and Arthur gives him his. When they turn to meet Percival as he rides up, both Arthur and Lancelot have swords in their scabbards.

In battle scenes archers fired volleys then broke ranks and charged their enemy. BUT during Medieval warfare bowmen were protected by pike-men and did NOT engage in hand-to-hand fighting. Therefore the scene of them braking ranks and charging was fanciful at best.

During the final sword fight, the long swords are clearly flimsy props. The blades bend and vibrate with each hit, one battler tried to spear his opponent and hit the rock face of the cliff behind him and the tip of the sword was crumpled like it was aluminum.

Before the first big battle, Modred and his men speak about Arthur and his men. One says "Is that all the strength that they can muster?" Another retorts "Old men and lame boys?" Yet they say this as they look at their opponents, who would be fairly obscured in their full armor and across a very wide field. At that distance and so obscured the only way that they only way they could have known that their adversaries were old men and boys was if it were in their scripts.

Gawaine shoots at an apple on top of a man's head. He misses and the arrow embeds itself in the post behind the man. The man pulls, with ease, the arrow out of the post. But the bow is a very powerful long bow and would have embedded the arrowhead tightly into the post. Accordingly, it would have taken a great deal of effort to have pulled it out of the post (at least more so than what the actor exhibited when he pulled the arrow from the post).

During sword fights, when ever anybody is run through, the blade is always withdrawn bloodless and clean.

When Lancelot throws Excalibur into the sea, he does so from a ledge high above the sea. And even though he throws Excalibur from high above, a splash is heard soon heard, heard much too quickly for an object thrown from such a great height. Further, that splash is heard above and despite the roar of the surf.

During the first big battle scene, a knight in red and a knight in blue are shown three different times during the battle getting killed by arrows, but from three different angles, yet you can clearly see it's the same men.

References to England are incorrectly regarded as goofs. The first known use of "England" occurred in 897. If King Arthur had been a 'real' king, he would have lived around the 5th or 6th centuries, however, it is more as a Middle Ages knight that he is presented in literature -- and in this movie. Knights in suits of armor (as portrayed in this film) began to appear in the early 15th century.

The country is referred to throughout as "England". There was no England in existence during the time traditionally associated with King Arthur - that is, shortly after the withdrawal of the Romans. The correct name is Britain or Albion.

It's not incorrect to show Medieval knights wearing purple surcoats. 'Purpure' (purple) was an established heraldic colour. The expensive Imperial Purple wasn't the only source of purple dye. It was easily available from lichens, and it could also be produced by cross-dyeing madder (magenta-red) with wold (blue). Even peasants are shown wearing purple in Medieval illuminations.

As is customary for Hollywood films about medieval times, the castles, armor, and general pageantry are designed for show and not accuracy. From Arthur's time in the 6th century, stone castles didn't come around until 500 years later, jousting about 700 years later, and full body armor not until 800 years later.

It is unlikely that so many of the knights would wear purple because of the cost of procuring purple dye before the discovery of mauve in the 19th century.

Morgan Le Fay (Anne Crawford) wasn't too young to be the mother of Modred (Stanley Baker), because in this version of the legend they are not mother and son - they're coeval adult lovers.