Visible crew/equipment: In the execution scene at the end, right as Wallace is being quartered, you can clearly see (on widescreen) a plastic spray bottle on the upper left part of the screen, presumably filled with fake blood.
Visible crew/equipment: At Stirling right before Wallace drops his sword and picks up an axe you can see some black duct tape on his sword. A man then swings his sword at the exact position of the duct tape. This is an obvious test take where they rehearse the scene, and was not meant to end up on screen. (01:27:00)
Continuity mistake: During the scene in which William Wallace is being executed, the camera pans the crowd and shows the ragged peasants staring in silence. An extra, who is a young woman with light hair and a dirty face and is standing near the front of the shot, stares directly at the camera for a few seconds while all the other extras look in a different direction towards the execution. (02:44:00)
Continuity mistake: During the first major battle scene, Wallace's sword has a leather looking binding around the blade at the hilt. As the battle progresses, the binding moves a third of the way down the blade and then back again.
Other mistake: In one of the very last scenes of the movie, when William's friend Hamish takes out William's sword to throw it as a sign of honor for William, when Hamish extends his arm back to throw the sword he only takes a step or 2, but he does not hit any of the men standing in formation directly behind him with this 5 foot long sword.
Continuity mistake: In Wallace's father's burial scene, when the young girl goes to give William the thistle, the camera goes to just their hands which are supposed to be those of young children. They are however clearly the hands of an adult woman and man.
Continuity mistake: In the battle scene where they flanked their forces and and were going to use the long wooden spears on England's knights, they already had the spears out when it showed England's horses coming closer. Just look around them. It only shows for a second when it is zooming in pretty fast.
Continuity mistake: At the end of the movie the executioner bends down to bind William's feet. The scene shows the rope starting around his feet and then a second later William is yanked into the air with a complicated noose-like knot holding his lower body to the ground. How did they make that knot so fast?
Other mistake: Near the end of the battle of Sterling after Wallace nearly hits one of his allies on the horse, look on the right side of the shot. An English man wearing metal armor is fighting some Scots. He doesn't make much effort, barely swinging his sword. The Scots fighting him also don't put up much of a challenge either.
Factual error: Some more errors about Princess Isabella: at the height of William Wallace's rebellion Edward I sends her as an ambassador to negotiate with Wallace (and spy on the Scots) instead she falls in love with Wallace. Princess Isabella was born in 1292: Wallace's rebellion was at its height during 1297-8, so she could have been no more than 6 at the time. (Somebody else has already observed that she was only 13 at the time of Wallace's execution.) Isabella's first language would (obviously) have been French, a 13th century Scotsman would speak either a heavily accented Scottish version of English, or Scots Gaelic, but Isabella has no communication difficulties in Scotland. The Wallace-Isabella affair is also absurd, since it is implausible that, at the height of a war, an unaccompanied young woman, let alone a princess engaged to the heir to the throne of England, would be sent into the heart of a war zone as an envoy and a spy.
Continuity mistake: At Stirling when the Scottish attack on horse, there is a scene where an Englishman is being sliced by a sword and is quite bloody. Then it cuts to him being run over by two horses and you can see that it is not the same man nor are there any traces of blood on him. Then it cuts to him falling to the ground and he is again quite bloody. (01:26:50)
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.
Revealing mistake: During the first large battle between the Scots and the English, there is a clear, quick shot of an English soldier getting quite eviscerated on the right side of his body. For a fraction of a second, you can see a couple drops of blood splatter against some sort of protective glass between the camera and the soldier.