I did this once and it was obvious the interviewer wanted me to point out his pet "gotcha." Not a great experience.

Yup, that's just one of the many ways to do a code-review interview wrong.

Each code sample should have multiple things wrong. The best people will find most (not necessarily all) of them. The mediocre will find a few.

Yeah it's really tempting when you discover an interesting fact to think "that would make an interesting interview question" and turn the interview into some kind of pub quiz. Happens with all forms of technical interview though. I mean 90% of leetcode questions are "this one weird trick".