Revealing mistake: After Wallace kills the Scottish noble in bed, he jumps out of the castle window into a river on a horse. As he is falling, you can see that the horse is a model and when they fall into the water one can see the fake horse bobbing around. (02:15:45)
Revealing mistake: At the end, Wallace's friend is charging in slow motion, and if you look closely you will see his battle axe flopping around like it's made of rubber. (02:49:50)
Revealing mistake: When Wallace walks up to the man who killed Murron and faces him. Look at the man behind Wallace and the man. You can actually see a car passing behind his head in the distance. (00:50:20)
Revealing mistake: In the scene where Wallace takes over the town after his wife is killed, watch as one of the English archers gets thrown off the scaffold and you can see him fall into a large pad.
Revealing mistake: When the scarlet chevron is charging towards Wallace and his horse is struck down, watch Wallace's sword, it never comes close to hitting the horse. (01:31:10)
Revealing mistake: In one of the major battles the old Scot gets his arm chopped off right over the wrist. You can see his prosthetic arm falling out of position after the cut. (01:27:00)
Revealing mistake: When the cavalry is charging the army, in one quick shot you can see a very fake horse do a flip when it reaches the front line. It's head is way down and the legs don't move, even when it's 'running'. (01:27:50)
Revealing mistake: When Hamish throws one of the English soldiers off his stand and he flies on to some wooden spikes, you can actually see the spikes bend as he falls between them. However when it cuts the man is suddenly impaled by one of the spikes. (00:49:30)
Revealing mistake: When the Scott gets shot in the buttocks during Stirling, there's a lot of blood already on his leg as soon as the arrow hits him. (00:25:05)
Revealing mistake: When Wallace rides into the village after his wife is killed, he hits the foot soldier with the mace-like weapon. When his horse is lanced, note that the lance is actually attached to the leather girdle on the horse, so, in effect, the animal is merely being pushed over.
Revealing mistake: As the funeral of young William's father and brother is over, a man lifts a shovelful of dirt and empties it onto the open grave of one of the men. As he does this you can see the fake body that is wrapped up bounce pretty hard, revealing that it is not in fact a real person but something made out of lightweight material.
Revealing mistake: William Wallace's footwear (as seen at the end of the movie) has metal eyelets. Either he was ahead of his time or wardrobe wasn't paying attention to detail. (02:40:20)
Revealing mistake: At the end of the battle of Stirling we see a Scotsman stab something with his sword and we can hear "Ouch". However there is no one on the ground where he stabs. He just rams the sword into the ground. Then he does it again and we hear "Ouch". Quite fun to watch. (01:27:55)
Revealing mistake: In the scene when William Wallace rides into Mornay's bedchamber to kill him, Mornay's body is replaced with a dummy several frames before the weapon strikes his face. The face is already disfigured.
Revealing mistake: When his wife gets attacked, Wallace jumps over a roof and you can clearly see him wearing modern black briefs.
Revealing mistake: Something very strange happens at the battle of Stirling. An arrow can be seen near William Wallace's right shoulder even before the English archers start shooting. Now where did that come from? It's there for about a second, so look closely. (01:20:45)
Revealing mistake: In the scene where Wallace comes back (right after his wife is killed), he throws two archers out of the tower. The second archer is supposedly killed on the palisade wall; but right before the camera changes, you can see the wall bending as he lands on it.
Revealing mistake: In the scene where Princess Isabelle gives Wallace the remedy to dull his senses, she pours the liquid in his mouth and then kisses him. Then on her way out, you can see Wallace swallowing before he spits out what is supposed to be the poison.
Suggested correction: Yes, you can swallow with a small amount of liquid in your mouth and not ingest the liquid. Not a mistake.
