This does not bother me, as it is generally irrelevant. As you already passed the technical screen, so your tech side on Perl has been recgonized already, pointing out those little bugs does not give you more scores. Especially something like autovivification, is even not a bug, some people can choose to disregard the autovivification feature in Perl for style reasons.

If there is a situation prompts you to mention it during or after the interview, there is no harm to mention it, but don't mention those intentionally. If I am the interviewer, and sense that someone is too eager to show off just because of some really trival stuff, I would strongly doubt how deep the person is both in terms of tech and personality, and put him to the bottom of the queue.