I hate anachronisms. They do nasty things to the suspension of one's disbelief. One of them can yank me right out of a story and make me want to shut the book or turn off the TV.
I remember the first time I heard the term: an English teacher in high school gave the example of a charioteer in the movie Ben Hur wearing a wrist watch. You can see the suspect scene here; looks to me like a metal wrist band, not a tick-tock.
Recently I read two stories that suffered from anachronisms. I only remember one: a nineteenth century character using the word "zillions." That struck me as unlikely so I went to the Google Ngram Viewer which lets you search for words or phrases by year.
I found several nineteenth century uses of zillion but most of them turned out to be AI misinterpreting a badly printed million.
As for the others, well, it turns out that Zillion is a family name, although I haven't run into any of them in my travels.
An 1894 issue of St Nicholas Magazine, a publication for children, features a highly offensive cartoon of an elderly African-American using the word "zillions" as an indicator of his ignorance. Charming.
I also found a 1934 play in which a character says that, since M is the 13th letter and Z the 26th, a zillion is twice as big as a million.
The Oxford English Dictionary did better, finding that in 1926 the Detroit Free Press said "We are willing to be most anything except an incubator for zillions of germs."
So, it is clearly an anachronism to put the word in the mouth of a nineteenth-century character. And that could have been the end of this piece, except that I happened to be in the process of editing a story I wrote, one set in 1910. (It's a sequel to this one.)
In my story a character said: "If they come after that they can pound sand.”
And in my editing process I thought: hmm... Would that have been said in 1910? Back to the Ngram viewer.
It was easy to find early examples of the phrase being used in an industrial context, but I was looking for the colloquial meaning: get lost, drop dead, go soak your head, take a long walk off a short pier, go pound sand...
By 1888 people were using it as an insult: "He doesn't know enough to pound sand." (Often followed by "...down a rat hole.")
But I found that in an 1898 issue of The Medical World, Doctor J.G.L. Myers complained about doctors lacking the patience to let the afterbirth come out naturally. "If you haven't time to wait and give Nature a chance, go and pound sand. You can safely hurry that job -- and let some doctor with a conscience have charge of the case." But he doesn't mean drop dead; he means go twiddle your thumbs.
I almost stopped there but I found a British site called Phrase Finder which changed things. It said that the phrase was an Americanism (check) and may be an abbreviation of "go pound sand up your ass." Ohh... The author of the site, Gary Martin, found a source much older than mine. From The Saint Paul Globe, August 1886:
I have always umpired base ball from the grand stand… Nothing affords me more pleasure now than to sit on a hard board in the grand stand and devote my time yelling, “Kill him!” “Cut his feet off.” “Aw, go pound sand” and other rhetorical gems at the umpire.
So, what do you know? My character back in 1910 could have used that phrase. But I took it out anyway. Because this may be the worst thing about anachronisms: Even if a word or phrase really was used in the time your story is set in, if your reader thinks it wasn't, or pauses to wonder about it, it takes them out of the story. And keeping them engaged is worth zillions.