Later, "Carol's" production supervisor, C.O. "Doc" Erickson, described the film as "overdone", saying, "It was too long, too tiring, and beat you over the head too much." Marc Scott Zicree, author of "The Twilight Zone Companion" (1982), has cited "Carol" as an example of Serling's more "didactic" writing. Serling biographer Gordon F. Sander noted that unlike much of Serling's screenwriting dealing with social change, "Carol" was depressing and did not end on an optimistic note, possibly because Serling in 1964 was influenced by the then-recent assassination of John F. Kennedy and the Johnson administration's escalation of U.S. involvement in the Vietnam War.