Lucy in the Swiss Alps - S5-E21
Other mistake: The Ricardos and Mertzes are trapped inside an abandoned cabin after it is buried by an an avalanche. They are rescued by an oom-pah band playing "La Cucaracha." When the band members enter the cabin, their clothes and shoes are completely dry, and they don't track in any snow or water. Then when the Ricardos and Mertzes follow them out of the cabin, they leave their backpacks behind.
Answer: According to Snopes.com, there is no definitive answer, but the mid-1960s is the most verifiable date with "The Munsters" being cited as the first, although others claim "The Brady Bunch" showed the first couple seen in a double bed. An early TV show from the late 1940s titled, "Mary Kay and Johnny" is also thought to have shown the married couple's bedroom as having a double bed, although probably not with them in it. However, this was when TV was aired live, and there are no surviving episodes, only anecdotal accounts.
raywest ★
Something that is funny is that in the movie "A Christmas Story," they show the parents having two twin beds in their bedroom. In a real situation, they should have shown them having a double bed. Lucy and Ricky had twin beds pushed together in an early episode, which would have been pushing television boundaries in that time.