The title refers to the Washington-Moscow hot-line used during the Cold War, known as the red telephone which was established after the 1962 Cuban Missile Crisis.
Michael Ansara (Grigori Malinoff) previously appeared in the original Voyage to the Bottom of the Sea (1961) movie as Miguel Alvarez, and would later appear in Killers of the Deep (1966) as Tomas Ruiz.
This episode takes place in May 1973.
The plot closely resembles the 1962 novel Fail-Safe by Eugene Burdick and Harvey Wheeler, whose film adaptation Fail Safe (1964) was first widely screened about a month before "Hot Line" aired. Fail-Safe is sometimes considered to have been plagiarized from the 1958 novel Red Alert by Peter George, which was adapted satirically as Dr. Strangelove or: How I Learned to Stop Worrying and Love the Bomb (1964).
Ford Rainey plays President Henry Talbot McNeal in "Hot Line" and Doomsday (1965). He also played an unnamed President in Irwin Allen's No Place to Hide (1965), with his stock footage later reedited into The Reluctant Stowaway (1965). Then, in Allen's The Death Trap (1966), he played President Abraham Lincoln.