Return of the Archons....when Landru 'summons' his people, they start to slowly chase Kirk and company. Kirk starts to go into an alley when several Landru zombies appear, blocking his way. His crew stuns them, then we see a shot of the Landru zombies in the street still walking towards Kirk. But wait...if you look closely, a couple of these Landru zombies are the same ones that Kirk and friends just stunned in the alley.