Star Trek: The Original Series, season 1, episode 15
Shore Leave
Summary
Captain Kirk orders shore leave for the Enterprise crew on a seemingly uninhabited planet in the Omicron Delta system. The landing parties begin to see strange sights, such as a White Rabbit a la "Alice in Wonderland", Don Juan, and a sword-wielding samurai. Also, Kirk sees (and fights) an image of Finnegan, a rival from his Starfleet Academy days. Spock discovers that the planet seems to be drawing a large amount of energy from the ship's engines, placing the Enterprise in danger.
Summary from Wikipedia, CC BY-SA 4.0.
Find out more
These links open the services in a new tab with the question pre-filled; the AI assistants may ask you to sign in. Their answers can contain errors.