Independance
I was just reminded of this item I noticed in 2010: Many versions of the U.S. Constitution have a transcription error (including, until they fixed it, the National Archives transcript), because the original contains what we would now view as a spelling error.
The Date Clause of Article VII mentions the date the Constitution was signed and also gives the year as counted from "the Independence of the United States of America" (perhaps an echo of the British legal practice of using regnal years). Or so say many print and online versions; the handwritten text actually says "Independance," as you can see for yourself.
Incidentally, a search through Gale's Eighteenth Century Collections Online database, selecting only the "Law" category and the date range 1775-1799, yields 65 hits for "independance" and 518 for "independence," so "independance" was either a variant spelling or an unusually common error, even in presumably edited printed text. (For more on changing writing practices and the constitutional text, see my "Jane Austen and the Second Amendment" post.)
And, yes, I was keenly aware that, when I called the National Archives to tell them that they had a spelling error in their official transcript of the Constitution, I must have sounded like a total crank. And that was even before I started on the yellow fringe around the flag …