Stardate: 5521.3--The Enterprise is dragged off course by Questar M-17, an imploded negative star mass, and meets a strange shapeless being.
original airdate--September 08,1973
Goofs: Between different shots, Sulu changes from sitting next to Lt. Arex to sitting next to a human.
- The lower half of Scotty's body from the waist down isn't drawn and painted in while he's on the bridge.
- After having beamed on to the alien derelict, the force field surrounding Kirk is part way off him as if the animator didn't center Kirk into the outline.
- After the alien entity had commandeered the Enterprise and starts coercing the bridge crew with an overhead weapon, Kirk and Spock are shown alternately wearing/not-wearing life support belts.
- When an abandoned alien ship is found, Spock estimates that it had been in orbit of a dead star for 300,000,000 years. Kirk exclaims that that is longer than life had existed on Earth. However, life has been on Earth for 3.7 billion year, about 10 times longer than the age of the alien ship.