During the scene where the Enterprise crew flee the police, there is an obvious stunt double of Brent Spiner driving the stagecoach.
When the Enterprise crew beam back up to the ship with Samuel Clemens, as the transport starts, Samuel Clemens looks up and puts up his arms defensively. As he rematerializes on the Enterprise, he is looking down instead of up.
In "Q Who?," Q mentioned that he had dealings with Guinan "two centuries ago" and even said "Guinan, is that the name you go by now?" In this episode in the 19th century before she met Q, she is still known as "Guinan."
Picard: I wish... I wish time would've allowed me to know you better.
Clemens: Well, you'll just have to read my books. What I am is pretty much there.
Clemens: Where are we? And when?
Riker: This is the 24th century, you're on Devidia II, and you're not supposed to be here.
Clemens: Well, it seems to me I have as much right to be in your time as you had to be in mine. I wanted to see how you've conducted my future affairs.
Troi: Your future affairs?
Clemens: The affairs of mankind.
Riker: But the disappearance of Mark Twain, one of the most noted literary figures of the 19th century?
Clemens: Thank you.
Riker: That's not supposed to happen.
Clemens: I only took advantage of an irresistible opportunity, as any good writer would.
Clemens: Young lady, I come from a time when men achieve power and wealth by standing on the backs of the poor, where prejudice and intolerance are commonplace and power is an end unto itself, and you're telling me that isn't how it is anymore?
Troi: That's right.
Clemens: (seeing Worf) A werewolf!
The "Time's Arrow" two-parter has a connection to the season 3 episode "Booby Trap" where Guinan had told LaForge that she is attracted to bald men because one had looked after her when she had been injured. See the second note to "Booby Trap."
This episode won Emmys for Outstanding Individual Achievement in Costume Design and Outstanding Individual Achievement in Hairstyling.
Alexander Enberg (the reporter), who is the son of Jeri Taylor, would later play Taurik in "Lower Decks" and the recurring character of Vorik on Star Trek: Voyager for several years.
Bellboy: Jack London
The bellboy is Jack London, famed author of "Call of the Wild." He was originally from San Francisco and later settled in Oakland. He had many odd jobs during his younger days, many of which the character mentioned in these two episodes.