I experimented a lot with 3.5 and the extent to which it would hallucinate. It was wild. It would argue with me and I'd say something was wrong and ask for its source. It would make up a URL. I would then give it my own URL and then it would start to agree with me based on the website I provided that it couldn't actually access. But sometimes it wouldn't agree, despite my "source", for reasons that didn't make sense. Or sometimes it would agree for reasons that also didn't make sense.

I also had it suggest there was emailing capability in the playground interface, or it would say that it emailed me something I asked for. It would claim to have abilities to do a bunch of stuff like this that it couldn't actually.

Also recently discovered it hallucinates dates and times and has 100% confidence they're correct