In the movie, Isabella of France marries Edward II, is sent by her father-in-law Edward I to talk to William Wallace, falls in love with him, warns him out of several traps, has an affair with him, and taunts Edward I about her being with Wallace's child while Edward lies paralyzed and unable to speak. Wallace is then executed, end of movie.

William Wallace was executed in 1305. Edward I did not die until 1307, and was in fairly good health up to that time (he was leading an invasion of Scotland at the time). Edward II did marry Isabella of France...in 1308. In France. Afterwards she came to England for the first time. She never met William Wallace or Edward I. Finally, her first born child, Edward III, was born in 1312. Unless Wallace had come back from the dead, there was no way for him to father that child.