The Mary Halstead Story - S1-E10
Revealing mistake: Mary dies at the end, but while Adams comforts Tom, it's apparent that her corpse is still breathing.
The Rex Montana Story - S1-E35
Revealing mistake: When Flint follows the Indians, there's a strong wind blowing. But the two puffy clouds in the backdrop sky never move.
The Rex Montana Story - S1-E35
Revealing mistake: When Rex interrupts the poker game, the camera pulls in for a close-up of the lantern - so close that we can see it's illuminated by a big round light bulb.