The Scots didn't paint their faces blue. The Picts did, but that was hundreds of years earlier.
There's no record of Wallace screaming "Freedom!" as he was being castrated and disemboweled.
And it's pretty unlikely that he impregnated Princess Isabelle since she was 4 years old and in France at the time the film takes place.
Isabella was actually pretty badass in a very "hell hath no fury" kind of way. She whisked her son, the heir apparent, to the safety of her family in France and then helped lead a rebellion army back to England that finally overthrew her husband who is among the worst, ineffectual kings in English history.