Like Estelle Getty, who plays her sister, Nancy Walker was actually about the same age as Bea Arthur and was heavily made up to look older.
Angela's husband, Carmine, must have died sometime between Christmas of 1955 and January 1957.
The woman in a black floral dress at the birthday party is the same woman who Sophia's boyfriend, Tony, cheats with in a later episode.
Sophia never clarifies whether the coins her husband threw in 1955 were worth $19 then or in 1987 when this episode first aired. If it was $19 in 1955, then it would have been worth roughly $79 in 1987. If it was $19 in 1987, then it would have been worth roughly $4.50 in 1955.