Revealing mistake: When D'Artagnan and Rochefort are sword fighting on the frozen pond, both fall through the ice in separate places. As each one flails about in the water, it's obvious that the broken ice pieces are Styrofoam. It also appears that what is supposed to be snow covering the ice is ground up Styrofoam, too chunky to be real snow.
The Four Musketeers (1974)
1 revealing mistake - chronological order
Directed by: Richard Lester
Starring: Christopher Lee, Faye Dunaway, Michael York, Oliver Reed, Richard Chamberlain, Raquel Welch, Frank Finlay
Continuity mistake: During the battle at the convent, one of the Cardinal's guards takes aim with his matchlock musket, is shot by Portos, and falls - along with his gun - into a hay wagon. But if you watch the falling scene closely, it is evident that only the man ends up in the hay; the gun should have fallen some place to the left of the wagon.
Athos: Leave now. Leave Paris, leave France. Get as far from that evil woman's grasp as you can.