If there's one you can't discuss for any reason (doesn't even have to be you forgot: could be an NDA) then it's already excused from the discussion.

An even half-decent interview is not adversarial: just like day to day work, it requires interpreting some level of useful subtext and some level of open communication

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I mean, you forgot the details so it's not like it's not like you're going to start monologuing if you just touch on it: "You know, there's a real doozy from X years ago where Y but the details escape me, more recently Z happened"

If there are none that you remember that are interesting: "There aren't many interesting bugs, but there was this really interesting product requirement, could we go over that?"