Gaffes

Addressing a crowd of his men, King Marke mentions that they all must ride off into the forest that night, citing a tradition to ride out on the night of the full moon. The camera then cuts to a shot of a waxing half moon, followed by one of the men riding off on their "full moon" ride.

In the beginning scenes, when young Tristan is carrying his rabbit in his hands past the market stalls, he gets a sprig of something to make his mum the bracelet, and the rabbit disappears from his hands. We know he kept it as it is seen in the scene immediately after inside the keep roasting over a spit.

At the end when they show the flashback of when Tristan and Isolde are in Ireland and Isolde is reading her poem, Tristan kisses her and she holds up her hands and she is not wearing her shell bracelet. But earlier in the movie during the same scene she is wearing it.

When Isolde is trying to talk to Tristan in the market his hair is parted to the side. When she pulls him off to the side, his hair is separated in the middle at his forehead, his having no time to move it that way, as Isolde was holding was holding his hands.

Neither Britain, England nor Cornwall were ever ruled by the Irish.

England is not visible from Ireland.

Every Irish king had lots of Irish rivals. None of them had the sort of unchallenged power that Donnchadh is shown as having. Britain in the 5th century was also very split, part-conquered by Anglo-Saxon settlers but anyone might be fighting anyone else.

The Irish did not 'regularly' attack Britain.

Isolde recites a poem by John Donne which was written about a thousand years later,

In the scene when the barons are gathered, Marke addresses one group as the group from York. Since this movie is set just after the Roman withdrawal from England, York would have still been known as Eboracum.

When Tristan doesn't show for dinner, there is a fork at his place setting. Forks were first introduced into England in 1608.

It is highly unlikely that Isolde would have worn a wedding ring. The Roman custom vanished and did not come back into vogue until the late Middle Ages. In any case, Marke certainly would not have worn one himself. A woman was her husband's property, and the wedding ring was a literal symbol of that ownership. The custom of men also wearing wedding rings is relatively new.

The poem Isolde keeps quoting is 'The Good-Morrow', written by John Donne (1572-1631), first published in 1633 after the author's death. "My face in thine eye, thine in mine appears, And true plain hearts do in the faces rest; Whatever dies was not mixed equally; If our two loves be one, or, thou and I Love so alike that none do slacken, none can die."

Marke's castle is stone built in the "motte and bailey" style with a keep and a drawbridge. These didn't exist in Britain until after the Norman invasion - about five hundred years after this film is supposed to be set. Britons, either Celts or Anglo-Saxons built large earthwork defenses or walled their towns with wooden palisades.

At the party when Melot is trying to talk to Tristan and Marke about his choice for second, Melot says, "You don't seem to know what you've done here," but the motion of his lips doesn't match the words.

The fresco showing a Roman couple is a copy of an iconic painting from a home in Pompeii, Italy.

The map in the movie shows Dunluce Castle as being further south than Bangor. Dunluce is actually significantly further North than Bangor.

The Cornish sent Tristan on a burning funeral barge to sea, but not only did it neither fully burn nor sink, but they failed to notice that he was alive, something Isolde discovers easily.

Although both are supposed to be from Dunluce, Bragnae has a Dublin accent while King Donnchadh has a Northern Irish accent.

Isolde's accent constantly veers between mild Irish and English, and at some points sounds almost American.

When Isolde tells Tristan that he can wash himself in the ocean, she clearly means the sea, as the ocean is on the west side of Ireland, not the east.