Blooper

Taran unchains the gate barring their escape from the castle. In subsequent shots, the lock and chains reappear and then, finally disappear.

As Creeper prepares the Horned King's drink, the goblet changes colors between shots.

When Fflewddur Fflam is locked up in the dungeon, the number of strings on his harp changes between shots from 5 strings in the wide shots and 8 strings in the close-up shots as they start to snap off. Then later on, the harp is back to 5 strings straightened out.

When Taran escapes the Horned King's Castle, he leaves the sword's sheath behind. However, when he is outside, he has the sheath again.

As the Horned King prepares to activate the cauldron, he first pulls away the tarp over the cart of dead warriors. The next shot shows the Horned King already holding up one of the corpses over his head.

When Taran is opening the gate to the drain before the castle is destroyed, the gate can be seen through his hands and the chains.

Before the film was released, several scenes considered too "graphic" were cropped out of the film. One particular cut involving a Cauldron Born killing a person by slicing his neck and torso created a recognizable lapse due to the fact that the removal of the scene creates a jump in the film's soundtrack.

When the little fairy girl says, "I bet they'll wake up soon!" her lips are moving but the boy fairy's voice is the one talking.

When Taran, Eilonwy and Fflewddur arrive at the witches' house, the witches are clearly shown turning them into frogs, and then back into humans. They then negotiate the exchange of Taran's magic sword for the cauldron. Why not just turn them all into frogs again and simply take the sword? That way they'd have both the sword and cauldron.

When the Witches confront Taran, Eilonwy and Fflam after the Castle is destroyed, they negotiate for the return of the Cauldron in exchange for bringing Gurgi back to life. When they arrived at the Witches house earlier, Taran and co. didn't know where the Cauldron was, and had to barter for it. But in this instance the Witches do not need to give them anything; they could simply take the Cauldron and leave, they have no reason to do a deal with them.