Dr. Quinn, Medicine Woman - S1-E1
Revealing mistake: While Dr. Mike is riding in the wagon with Charlotte and her children, when Charlotte says, "I'd like to ring Sully's neck," a vehicle is visible behind Charlotte's head driving toward the left side of the screen. (00:20:05)
Revealing mistake: When Rankin is gored by the white buffalo, in his last closeup the wood plank and steel posts are visible at the back of the animal head prop, at the right side of the screen. (00:44:30)
Revealing mistake: Obvious lip liner on Michaela in the end scene.
Answer: A Cooper was someone who made various things out of wood including wooden caskets and even barrels.