Continuity mistake: When heavy cavalry charge the Scots in the first major battle, the camera cuts to a quick shot of the Scots holding the long spears before Wallace actually gives the signal.
Plot hole: In the scene where William takes Murron for their initial ride, he shows up in pouring rain, yet all further shots show the two of them totally dry. The tone of her mother's voice when they get back suggests they did not spend the night together, and the whole sequence appeared in a couple hours. They could not have gone from soaking-wet to bone-dry that fast.
Factual error: In the night scene after Malcolm Wallace's funeral we see the silhouette of a man playing bag pipes. Argyle tells William that they are outlawed tunes played on outlawed pipes. However, the bagpipes have only ever been banned twice in Scotland: in 1560 after the Reformation and again in 1746 after the Battle of Culloden (evidence for bans on bagpipes in the 18th century is weak at best). In the late 13th Century the bagpipe enjoyed similar popularity in England, although Scottish bagpipes were particular to the region, and had an established cultural importance. Whether these early bagpipes were as strongly associated with highland culture as later forms of the instrument is unclear; lowland and border musical tradition is more closely linked with small pipes.
Factual error: At the battle of Falkirk, the Irish soldiers fighting for Edward change sides at the last moment and go over to fight with the Scots. In reality, there were no Irish troops present at the battle. The only troublemakers amongst the English army were the contingent of Welsh bowmen who showed a reluctance to fight Wallace but this was more out of fear rather than sympathy for the Scots.
Continuity mistake: Just before Wallace picks up the archer to throw him over the ledge, you can the archer has a tin looking hat around his head with part of his suit covering his head below the hat. In the shot from in front of the ledge when Wallace is throwing him off the cap has now disappeared before he has been thrown. The following shot as he is falling its a bit hard to see his cap but you see it come off. (00:50:45)
Continuity mistake: In the scene where William Wallace charges after the king's brigade after the Battle of Falkirk, and Robert the Bruce (disguised) turns and charges at him with a lance, Robert is wearing two distinctly different silver helmets before he hits Wallace and after. These two helmets are seen interchangeably in the preceding scenes also. (02:02:00)
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.
Continuity mistake: At the end, when the main executioner bends down, his cloak shifts and you can see he is wearing brown shoes with red rubber soles. These rubber soled shoes are worn today and had not been invented yet.
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)
Continuity mistake: When Wallace arrives at the home of Murron to invite her for a ride in the rain, the mother's head covering changes several times between shots. Sometimes it has the yellow fringe close to her face and other times it does not have the fringe at all. (00:29:40)
Continuity mistake: In the scene where the English on horseback charge the Scots, look at the lighting on the ground. One moment it appears to be sunny, and the next it is cloudy.
Continuity mistake: At the very end of the movie, watch the man standing to the left of the Bruce at Banickburn. In a shot from behind, there is a man with very short and curly hair. In the very next shot, from the front this time, a different man with very long and straight hair is to Robert's left.
Continuity mistake: When William realizes that the Bruce has been bought by the King, he gives up and lies on the ground. Earlier, he had been hit with an arrow and if you look hard you can see the arrow move when he lies down. This shows the arrow to be attached to his clothing and not actually piercing his body.
Continuity mistake: During the scene in which Steven (the crazy Irishman) joins up with William Wallace and they converse about killing Englishmen and such, pay attention to Steven's forehead. It's very obvious that the scene was composed of multiple takes because of the way that repeatedly throughout the scene Steven's hair changes. There are a couple of locks of hair that go from being stuck across the middle of his forehead to being off to the side with the rest of his hair. (01:09:00)
Factual error: Prince Edward was not a mincing homosexual stereotype. His homosexuality did not become obvious until after he became king and started taking male 'favourites'. Before then he was regarded as the perfect prince.