Austrian-American actress Celia Lovsky (Sister Olaf)] played the original T'Pau, the Vulcan diplomat, judge, and philosopher who presides at Mr. Spock (Leonard Nimoy)'s wedding in "Amok Time (1967)".
The title refers to a line in the 1934 Christmas/winter song "Winter Wonderland" written by Felix Bernard and lyrics by Richard B. Smith: "walking in a winter wonderland..."
Woodrow Parfrey (Weatherman) was a popular character actor in the 60's fantasy sitcoms, appearing in the episode I Confess (1968) as Gen. Stanton (inquiring about Samantha's nationality) and 4 times in I Dream of Jeannie (1965).
When Sister Bertrille (Sally Field} visits her friend Señor Ramirez (Alejandro Rey}, the street and fountain set that represents the establishing shot of downtown San Juan is the same as the one used for the town of Esperanza in the later episode Tonio's Mother (1968).
This episode first aired four days before Christmas 1967.