Sulu, Uhura, and Chekov do not appear in this episode. Scotty does not appear on screen but has several voice-over lines. In no other episode are only three regular members of the crew seen in person.
The name of the librarian Mr. Atoz is a play on the phrase "A to Z." Author Jean Lisette Aroeste was a UCLA librarian at the time she wrote this script.
The title is taken from "Macbeth" by William Shakespeare, Act 5, Scene 5: The title character speaks "Tomorrow and tomorrow and tomorrow, / Creeps in this petty pace from day to day / To the last syllable of recorded time, / And all our yesterdays have lighted fools / The way to dusty death."
According to the stardate, this episode is chronologically the last of the series, even though its production number and air date are earlier than Turnabout Intruder (1969). This is therefore the last voyage of the USS Enterprise in the original series. This is also the last time-travel episode of the original series.
Part of the set depicting the surface of the ice age planet where Spock and McCoy are transported was recycled from the MGM film Ice Station Zebra (1968), made the previous year.