Continuity mistake: During the archery constest, in one scene Prince John has a ring on his right paw with no jewel, then all of a sudden the jewel appears. a few scenes later he has three rings on that paw, and later he has no rings at all.
Continuity mistake: When Falfa's Chevy flips over, we can see that it has no fuel tank at all in it. However, in the next shot the car now has a visible fuel tank, and it explodes.
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.
Continuity mistake: When Barbra Streisand meets Robert Redford on the street at the end of the film, the camera shoots her from behind and her coat collar is standing up. When the angle shifts to the front, her collar is neatly in place.
Continuity mistake: In one scene the actress is wearing a tight fitting sweater which clearly shows that she is wearing a bra. In the next shot she stands up to say she is off to have a shower, whips off her top and - you've guessed it - no bra!
Continuity mistake: In the bedroom scene, Barbara Windor gets her dressing gown caught in the bed spring and has to take it off. When Sid James tries it on, he has no trouble removing it from the bed.
Continuity mistake: While throwing clothes and lamps at each other, Vicky throws one shoe and then the next one, but, later, her shoes are back, and she throws them again.
Continuity mistake: When Webster steals a huge diamond, one of the guards comes to from the chloroform and raises the alarm before Webster has left the building. As he hurries to leave, Webster gets shot in the left arm, and he must use a truck as a battering ram to break through a garage door; he does this, but the garage door is now on the front of the truck, obstructing Webster's view, until, suddenly, it vanishes - all that's left are the side bits of the garage.