Episode Titles -- sources
A lot of this show's episode titles are quotes or puns/variations on quotes (though in some cases I may be seeing things that aren't there). If you think I've missed something, please let me know.
Here's my take on Season 1's titles (I'll put subsequent seasons in separate posts):
1.01 "Love Is All Around" -- blatant plagiarism from the theme song's lyrics!!!
1.02 "Today I am a Ma'am" -- pun on a key line from the Bar Mitzvah ceremony, "Today I am a man."
1.03 "Bess, You Is My Daughter Now" -- variation on the song title "Bess, You Is My Woman Now" from the 1959 musical Porgy and Bess. (I doubt that a network would allow this title nowadays.)
1.04 "Divorce Isn't Everything" -- presumably a variation of the common saying "money isn't everything."
1.05 "Keep Your Guard Up" -- an old saying, though in this case the word "guard" may be something of a pun, if the former football player was a guard.
1.06 "Support Your Local Mother" -- this sort of slogan has been used so often that I'm not sure what the original was! All I can think of right now is the hilarious 1969 James Garner movie Support Your Local Sheriff (which was hardly the first).
1.07 "Toulouse-Lautrec Is One of My Favorite Artists" -- presumably an original.
1.08 "The Snow Must Go On" -- pun on "The show must go on."
1.09 "Bob and Rhoda and Teddy and Mary" -- patterned after the 1969 movie title "Bob & Carol & Ted & Alice."
1.10 "Assistant Wanted, Female" -- worded the way help-wanted newspaper ads used to be.
1.11 "1040 or Fight" -- play on James K. Polk's 1844 presidential-campaign slogan, "50-40 or Fight" (referring to the border between the US and what is now Canada), with "1040" referring to the US income-tax form.
1.12 "Anchorman Overboard" -- variation on the traditional boating alert "man overboard."
1.13 "He's All Yours" -- common saying.
1.14 "Christmas and the Hard-Luck Kid II" -- episode has a similar theme (having to spend Christmas more or less alone in one's workplace) and basically identical title as a 1966 episode of Marlo Thomas's sitcom That Girl, both written by James L. Brooks -- thus the "II" (as explained more fully here: https://www.metv.com/stories/watch-that-girl-gives-us-the-holiday-prequel-to-mary-tyler-moores-christmas-and-the-hard-luck-kid.
1.15 "Howard's Girl" -- possibly a faint echo of the title of the 1962 pop song "Bobby's Girl," but otherwise apparently original.
1.16 "Party Is Such Sweet Sorrow" -- pun on Shakespeare's "Parting is such sweet sorrow" from Romeo and Juliet.
1.17 "Just a Lunch" -- quote from Mary. Possibly also a take on "just a hunch," since it's clear to Mary that Markham's character wants more than lunch.
1.18 "Second Story Story" -- from the expression "second-story man" for a burglar who enters through an upstairs window (but note that Mary lived on the third floor till Season 4, when they showed the exterior of a similar but different house where she apparently did live on the second).
1.19 "We Closed in Minneapolis" -- Broadway-bound plays are often tested in other cities, and if not received well, they're said to have "closed in Boston" or wherever. (Ironically, Holly Golightly, a 1966 musical version of Breakfast at Tiffany's starring Mary Tyler Moore, had not made it to an official Broadway opening.)
1.20 "Hi!" -- just something Mary often says.
1.21 "The Boss Isn't Coming to Dinner" -- based on the common theme of inviting one's boss to dinner, with perhaps just a hint of the 1967 movie title Guess Who's Coming to Dinner.
1.22 "A Friend in Deed" -- from the old saying "A friend in need is a friend indeed" (though it's not clear just how this applies to Mary's old summer-camp buddy).
1.23 "Smokey the Bear Wants You" -- variation on the WWI recruitment slogan "Uncle Sam Wants You," tweaked for a forest theme (though purists will argue that the mascot's official name is just "Smokey Bear," with no "the").
1.24 "The 45-Year-Old Man" -- a literal description of Lou, with perhaps just a hint of the 1960s Mel Brooks character "the 2000 Year Old Man."