The Psalms.
The ancient Hebrew manuscripts had no breaks between the psalms, but when it was translated into Greek in the Septuagint, the notes were attached to the beginning of the adjacent psalm. Every translation since has copied that and stuck them at the top, as a superscript, even in my NIV today.
BUT, struggling to find meaning in these notes, around 100yrs ago, some bright spark decided to look in the bible itself (often the best place for answers) to see if there were any other psalms which may help. He found two (Isaiah 38:9-20, and Habakkuk 3), and discovered the translators got it wrong all along!
And he is correct, take a look. The latter is the clearest example where it begins with (3:1) "A prayer of Habakkuk the prophet. On Shigionoth", and ends with (3:19) "For the director of music. On my stringed instruments". That is the last line in book of Habakkuk, so it can't belong to anything following.
So here is proof that the portion directed to the musicians should be a subscript, not a superscript!
Now, one example where this is significant is Psalm 8, which includes the line 'what is man that you are mindful of him, the son of man that you care for him'. The psalm is clearly about the messiah. Now if we steal half of the superscript from Psalm 9, we have 'For the director of music. To the tune of 'the death of the son'. Which is a bit more significant. But I have also seen it explained that this line could well be translated 'the secrets of the son', also significant.
What to make of all this? Not too much I guess, but it is a point of interest. And a good example how even the earliest translators have clearly made a mistake.
Enjoy.