The use of Em Dash within quoted speech
I am wondering if I can use the em dash with a quote. If I can use them, I am curious of whether it would mean that the writer is telling the audience that information, or if it means that the person speaking had said the entire sentence, yet the transcriber added the em dashes in order for the sentence to appear grammatically correct to the reader.
Can I use them in a quote? And if so, can I use them to show what the speaker said? Or do they only imply that the author is commenting or supplying new information?
"We ended up going to Red Robin — the only restaurant still open at that time — to get some food."
"We ended up going to Red Robin, the only restaurant still open at that time, to get some food."
Yes; the em-dash within the quotes is part of what the speaker has said. If the transcriber wishes to comment, then brackets [ ] (in UK, square brackets) are normally used. For example,
We ended up going to Red Robin [which was the only restaurant open at the time] to get some food.
This is an interpolatory comment by the writer/transcriber explaining why Red Robin was chosen. Also note that brackets (or for that matter, parentheses, semicolons, colons, and brace brackets) should never be italicized (for one thing, they look weird).