The title comes from the World War I and World War II recruitment posters showing the picture of Uncle Sam telling people that he wants you for the Unites States' Army. "Uncle Sam Wants You!"
When policeman Steve Sloan (Barry Van Dyke) first encounters a priest in the church (actually Dr. Mark Sloan played by Dick Van Dyke) he says, "Hello Father." The priest refers to Steve Sloan as Son, as priests refer to other males. This has triple meaning as Mark Sloan was posing as a Father in the church, and was the biological father of Steve Sloan, while in real life Barry Van Dyke is Dick Van Dyke's biological son.