The Three Musketeers (1973)

Continuity mistake: At one point D'Artagnan reaches the Duke of Buckingham, who is on a hunt. He has just killed a stag and his hands are covered in blood. D'Artagnan rides up and offers him a note from Queen Anne. He wipes his palms with a cloth before he takes the note, but his hands are still covered with blood up to and above the wrists. When he reads the note, he and D'Artagnan take off on foot for his castle where they go into a private room behind the walls. Suddenly it is apparent that his hands are perfectly clean right down to his scrubbed fingernails and, without explanation, the plot-heavy sequence continues.

Porthos: May one ask - delicately - the cause in which we're expected to die?
Aramis: When you go on a campaign, does the King give his reasons? He says, "Porthos, fight!" and you fight.
Porthos: Oh, I do, I do.
Aramis: Then let's go and be killed where we're told to! Is life worth so many questions?

Trivia: Oliver Reed almost died when he was stabbed in the throat during filming of a swordfight scene.

Question: Why was Cardinal Richelieu's costume changed from red to purple?