A dictionary of Confusable Phrases: More Than 10,000 Idioms and Collocations

Note: 
The expression does not fully correlate in meaning with
the phrase latest thing , the— = last thing, the 3: The sketch
of Bain’s facsimile machine of 
1
843 will shake up those who
think the fax machine is the latest thing in technology.
one final thing —(also: one final word) is used to introduce a
parting comment or advice: And one final thing, don’t haul
around a lot of expensive camera stuff. It just tells the thieves
who to rob.
last word, the • last words
last word, the —
1
. (also: last thing, the) smth. that is most
up-to-date; smth. that cannot be surpassed: These three white
trucks represent the last word in modern emergency equip-
ment. 2. said of a person or thing that is as bad as it is possible
to find: Don’t talk to me about untidy kids. I’ve got two at
home that are the last word.
Note:__The_expression_does_not_correlate_in_meaning_with_the__phrase_one_final_word'>Note: 
The expression does not correlate in meaning with the
phrase one final word—(also: one final thing) used to introduce
a parting comment or advice: “One final word, keep your chin
up.” “Good advice!”
last words —an utterance that was the last smb. made before
dying: The victim of the crime, in her last words, declares,
quite unprotestingly, that it is what she expected.
Note:
The expression is not equivalent in meaning to the phrase
famous last words—
1
. the final statement made by a famous
person who is dying: James Lawrence, whose famous last words
were “Don’t give up the ship,” is buried next to steamboat
inventor Robert Fulton. 2. (ironic) a remark or prediction likely
to be proved wrong by events: “With modern technology, we
can climb Everest in half the time it took Hillary in 
1
953.”
“Famous last words!”