The Communicator

Returning from covertly observing a preatomic-era alien world on the verge of war, Lieutenant Reed realizes he lost his communicator somewhere on the planet. Archer and Reed return to recover the lost technology, only to find the natives found it first. Captured and interrogated as spies, Archer and Reed find themselves doing even more damage to the culture when they are scanned and found to belong to another race.

Synopsis adapted from TVmaze (CC BY-SA 4.0)