Revealing mistake: In one scene, when Jack is in the dungeon talking to the fairy, you can clearly see that the "fairy" is nothing more than a light on a thin piece of wire. The wire can be seen quite clearly for two shots.
Revealing mistake: The two unicorns are a stallion and a mare in the movie. But both horses used were clearly stallions. This can be seen quite well when the "mare" is jumping around after she comes upon the stallion with his horn removed; a full shot of the male horse anatomy.
Continuity mistake: When the daylight hits the doors to Darkness' sacrificial chamber, Blunder the ex-Goblin stands right in front of them. But when the door panels are blasted out of their hinges, he is nowhere to be seen.
Revealing mistake: Whenever Darkness throws back his head and laughs, you can see a cap on one of his back teeth. Since when does the Lord of Darkness need dental work?
Audio problem: After Jack dives into the water, Lily's first scream doesn't fit.
Revealing mistake: In the opening scene where you see the bear walking by, you next see a deer standing. The deer has a rope around its neck and is tied to something.
Revealing mistake: There is a winter scene where Jack is wearing a cloak that is securely fastened at the collar with a huge modern safety-pin.
Continuity mistake: In the US released version the scene with Meg Mucklebone (green swamp creature) was severely shortened. The problem is that one second Jack has his shield and then when he beheads Meg, the shield is hanging in a tree behind Meg. In the director's cut Meg grabs Jack's shield and uses it as a mirror.
Other mistake: Jack compliments Lily on her ability to speak to a bird she holds in her hand but no bird call is heard from Lily in the European version. In the American version her bird call is heard.
Revealing mistake: The two arrows Gump has shot into Darkness' neck (and which are still in it as he attacks Jack) have wooden or plastic heads.
Continuity mistake: In the introductory text, Lily is written with a Y whereas in the credits, Lili is written with an I.
Continuity mistake: In one shot, as the goblins are chasing after the wounded unicorn, four goblins are seen riding around a bend in a shot that presumably was taken from the first part of the film where the group was made up of four.
Revealing mistake: When Jack is swordfighting with Satan, you can clearly tell that Satan's face is a mask. There are fibre reflections in his mouth.
Continuity mistake: Brown Tom is shot in the hat by the Goblins while defending the last Unicorn. In the scene where it happens, the arrow pierces the hat right below its tip, but when he recovers consciousness, the arrow is placed in the brim.
Revealing mistake: When Blix fires a fireball at the goblin in the woods with the unicorn horn, the flame sets fire to the goblin's behind; he sits in a bucket of water to put it out but the flame goes out before he actually sits right down or the 'hiss' of steam appears.
Continuity mistake: Jack apparently fires an arrow at Darkness just as Lily severs the unicorn mare's chain, but as he lowers the bow, he is still holding the arrow. Shortly but well seen in two scenes right after this.
Continuity mistake: When Jack first dives for the ring and the forest lake freezes over, Jack pounds at a layer of transparent ice. But when he finally breaks through, the ice fragments are milky-white.
Revealing mistake: After Lily runs into Nell's house to escape the goblins, the baby in the crib is a doll.
Revealing mistake: When Meg Mucklebones rises up out of the swamp, you can see the cross-shaped 'stilt' behind the actor, to which he's attached to, as he sways forward and backward.