In the opening scene, immediately following Elora's birth, Sorsha is speaking with a woman who sounds suspiciously like Bavmorda, and states, "She bears the mark." However, Sorsha leaves the cell saying, "I must tell my mother," which would imply that Bavmorda was not present in the cell. Further, the only two remaining people in the cell when Sorsha leaves (aside from the infant) are Elora's mother and the midwife, neither of whose voices sounds remotely like the woman's voice heard earlier. This would suggest that in an earlier version of the script, Bavmorda was intended to be in the cell when the child was born, but the scene was changed later and the dialogue not re-recorded.
Before the journey to return the Daikini baby, Willow is seen with the papoose on his back, then off, then he puts it on again.
While hanging in the cage, Madmartigan's hand goes from fiddling with a chain on the side to gripping the front bars between shots.
When Fin Raziel shows Bavmorda that she has Cherlindrea's wand, her clothes, hair and skin are completely wet. In the next shot, she is now totally dry.
Madmartigan has his legs hanging out of the cage. In the scene directly following it, he has his legs in the cage and crossed.
The animal that Madmardigan calls a "muskrat", looks nothing like a muskrat - except that "Willow" (written by Star Wars creator George Lucas) is not happening on Earth, but upon the large moon of a giant planet - so all dialogue is effectively a translation from some alien language.
Just after Willow's wagon goes over the fallen tree during the cart chase, one of the horses steps on the tree and leaving an imprint showing that it is made of foam.
While sliding down the hill on the shield, runners are visible from the sled that was used.
While sliding down the snow hill on the sled, a very modern glove can be spotted on Madmartigan's left hand.
Just before arriving at the Castle of Tir Asleen Razel (in the shape of a rook) warns Willow of the approaching soldiers. A rock is briefly seen flying across the screen, aimed at the bird, to get it to fly away on cue.
You can see the wire supporting Madmartigan when he is on the catapult outside the castle.
When Willow gives Elora to Madmartigan, what is heard is, "Goodbye, little one," when originally, he said, "Goodbye, Elora." It was after the scene was shot that the people realized that Willow didn't know Elora's name at this point.
After the cart chase, when Willow and Madmartigan are hiding, enemy horses gallop past with the sound of barking dogs, but without any actual dogs to accompany the sound effect.
After Madmartigan rolls down the hill inside the giant snowball, a watchman shouts out that the soldiers are coming. Given how long and fast it took them to slide down, how did they get there so fast? Also, you hear clear clip-clop hoof-beat noises from the horses as they trample through loose powdery snow.
When the brownies kidnap Willow and tie him up, he asks, "Where did you get that baby?" But the movement of his lips doesn't match what he's saying.
During the tavern scene where Madmartigan is about to meet Llug for the first time, the woman he was sleeping with says, "Cover your face!" When the camera is pointed at her and Madmartigan, however, her mouth never moves.
When Fin Raziel, as a goat, butts a soldier off the bridge, the hands of the goat wrangler can be seen guiding the goat to its target.