Edward Asner had worked with Florence Lake prior to Lou's First Date (1973), in the Joan Rivers-penned TV comedy film, The Girl Most Likely to... (1973).
Lou's date, Mrs. (Martha) Dudley was the flower girl at Thomas Alva Edison's wedding. Edison's second (and final) wedding was in 1886; assuming Mrs. Dudley was at least 4 then, that would put her at 91 as of the air date of this episode.
In a mid-70s interview, Mary Tyler Moore remembered the cast becoming exasperated with Florence Lake. It seems she didn't see the character as elderly and feeble as written. Moore said Valerie Harper took special time with Ms. Lake to get the performance needed from her.