Corrected entry: Francesca gives Guardi the note via the pig that "your services are no longer required," yet it is stated later that Guardi can neither read nor write.
Corrected entry: In the scene where Casanova and Francesca are going to be hung, notice that there is no trapdoor under their feet. This obviously was for safety reasons, but they could have at least painted lines to make it look like there was a trapdoor. It's most noticeable when they are fleeing the scene from on top of the gallows.
Correction: The gallows are operated by a winch. Once the execution would commence, they would be lifted off their feet by the nooses. This method causes a slow and agonizing death by strangulation, rather than a quick death due to a functional decapitation (broken neck) of the long drop.
Corrected entry: The historical Casanova's first name was Giovanni, not Giacomo. It may be that Giovanni Bruni, who, according to the movie, assumed the mantle of Casanova and later wrote down the many exploits of the legend, went down in history as Casanova, not Heath Ledger's character.
Correction: This is all wrong: the real name of Casanova was GIACOMO Casanova, not Giovanni, as you can see here: http://en.wikipedia.org/wiki/Casanova. The film is correct.
Correction: That is not true, it wasn't a mistake, because he looked at the paper not knowing what it said.