It’s so hilarious it makes me wonder if some of it is scripted.
There is a fair amount of editing and the people involved are usually good comedians* so I suspect the writers provide topics that have a lot of potential and rely on the funny people to hit those out of the ballpark. I wonder how long each show would last if it wasn’t whittled down.
*Jo Brand being the main exception.
I believe that there’s two hours worth of recording that gets whittled down to half an hour (or 45 min for QI XL), so there should be plenty of material.
It’s edited down. There was a q+a thing with the production team a while back where they said that first timers often get a bit of a clue about the topics beforehand, which is understandable I think. It’s likely very intimidating otherwise. There’s been a few hints that one of the regulars asks for that too, but never confirmed by anyone (Jimmy Carr I’m betting)
Stephen gets a big load of info on his cards about the topics, but he’s clever enough to wing it most times.
ETA: the editing down is why British panel game scoring usually makes no sense - it’s not the point anyway
By an interesting coincidence, I stumbled upon “The Making of QI” just yesterday, and while they didn’t say it straight out, the implication was it’s mostly/all unscripted.
I always thought the scoring on British panels shows followed the Numberwang metric.
Most regular panel game comedians have years of the kind of improv experience gained from other panel shows (on both TV and radio), so their comedy brains are ticking over 30 to the dozen most of the time.