V: Remember, remember, the fifth of November, The gunpowder treason and plot. I know of no reason why the gunpowder treason should ever be forgot.
As V attacks all of Creedy's men with his knives, in one shot he cuts one man's neck, and blood sprays onto the man's face, but in the next shot as the man falls, his face is clean.
In the scene where Evey gets her hair cut, it was Natalie Portman's real hair they cut. They had only one shot to capture that scene, and everybody was quite nervous if the scene would turn out usable.