In Muriel's flashback, she and Henry are discussing the 1960 Presidential candidates, and Muriel says she likes Kennedy, stating that "he's cute" and "he says that someday soon we'll be sending people to the moon."
Henry replies "I know who I'd like to go first," and Muriel correctly assumes he meant her mother.
Muriel's mother was played by Audrey Meadows, who was best known for playing Alice Kramden on "The Honeymooners".
"The Honeymooners" was well known for the recurring joke in which Ralph Kramden (played by Jackie Gleason) threatened to send his wife, Alice, "to the moon" (while clenching his fist in her direction).