Web of Death - S1-E2
Continuity mistake: If you look at the victim lying on the floor when Ferro just killed him, you can spot a rather noticeable hem of his nightrobe sticking out from under his leg. When later, Kojak gets on the crime scene, nobody has touched the corpse yet but the clothing has been tucked in. (00:06:10 - 00:13:40)
Beyond the Farthest Star - S1-E1
Continuity mistake: There is an alien in a Starfleet gold shirt sitting next to Sulu. For a second, there is a human in a Starfleet red shirt, then it goes back to the gold shirt alien.
A Community of Victims - S3-E3
Continuity mistake: Officer Ripley's shoes change from black to white as he chases the ambulance, then back to black.