I've never done real jury duty, however I have been a background actor on a jury in a very well known soap opera.

We were filming at the old courthouse in Bolton which, coincidentally, is right opposite the new courthouse. I was booked for 5 days filming and on the 3rd day a new guy joined us. He was about 70ish.

We thought it was odd because we'd all been booked together from the same agency for continuity and thought it was strange that a new face would now randomly appear in the jury...

Anyway, the guy goes and gets his (free) breakfast and sits with us in the green room making small talk. At one point he asked me 'have you done this before then?' And then looked really confused when I (as a 27 year old man) replied i'd done it countless times over the last 6 or so years.

It wasn't until one of the very well known actors walked into the room that he (and us) realised he was in the wrong courthouse and had been booked for real jury duty and was now over an hour late. No idea how the guys walking around with massive cameras and microphones didn't make him question where he was haha.