Learn English – What does an exclamation mark inside parentheses “(!)” mean

I think if you ask the experts who would claim that they know what the “correct” way to punctuate something is, they would tell you that a sentence may only have one terminal punctuation mark—that is to say, neither “?!” nor “!?” is correct.

So, no matter what order you use, you’ll never please those people. The Corpus of Contemporary American English has 3742 examples of “?!” and 1197 examples of “!?”. Clearly both orderings enjoy substantial usage, although it does appear that “?!” enjoys a majority of usage, probably because most sentences that get the double punctuation treatment are syntactically questions that have an exclamation point added for emphasis.

Edit: I checked in the British National Corpus, and it has 224 instances of “?!” and 121 instances of “!?”.

Regarding "What happens when there's a question mark and only part of the sentence is a question?" and your three suggestions, my opinions are:

• I was distracted by a plane (or was it Superman?) ‒ Is missing period.
• I was distracted by a plane (or was it Superman?). ‒ Is ok
• I was distracted by a plane (or was it Superman)? ‒ Treats whole as question

I don't have definitive authorities to support the above choices. I have seen only three webpages that even remotely address your question:

• englishplus says

  In a sentence containing a parenthetical expression, any punctuation belonging to the main sentence goes outside the parentheses.

• wowwritingworkshop says

  A sentence in parentheses within another sentence does not take a period, because the period is reserved for the main sentence (questions and exclamations, however, must have their respective marks!).

• brians at public.wsu.edu says

  Normally a sentence’s final punctuation mark—whether period, exclamation point, or question mark—goes outside such a parenthesis (like this). However, if the material inside the parenthesis requires a concluding punctuation mark like an exclamation point or question mark (but not a period!), that mark is placed inside the closing mark even though another mark is outside it. This latter sort of thing is awkward, however, and best avoided if you can help it.

Note, rather than using parentheses I would word the sentence as

I was distracted by a plane; or was it Superman?