At one point Carol Burnett "accidentally" hit's Julie Andrews' in the stomach while taking a bow (this was scripted as part of the number they had just performed). Just before the show Andrews had found out she was pregnant and she and Burnett had decided not to do the hit, but Burnett simply forgot. As soon as this happens you see Burnett break character and ask if Andrews is OK.
In one sketch "The Sound of Music" is parodied three years before Julie Andrews starred in the movie version. (This clip is included on the 45th Anniversary Blu-Ray of the movie The Sound of Music (1965).)