Continuity mistake: In this episode, Rudy is riding her bike around the house which is right on the corner of a block. Since when is their house on the corner?
Continuity mistake: Cliff says "a young trumpet player while sitting in the bandstand watching the dancers". But in all the later episodes, Russell plays the trombone, and he had been for a long time.
Continuity mistake: After Clair turns off the record, the folder on the table changes position.
Continuity mistake: When Theo puts the phone down, the handset cord is next to the phone. The next shot it is now under the phone, when the phone rings it is now next to the phone again.
The Dentist - S2-E16
Continuity mistake: The amount of orange juice in Cliff's cup changes - you see him filling his cup, the next shot it is almost empty, a couple of shots later it is now full again.
Continuity mistake: The amount of milk in Robert's glass changes a few times throughout the scene in the kitchen.
Chosen answer: That is the song "Open the Door Richard."