Short synopsis: Cohen used Google's Bard to draft up an argument that he sent to his lawyer. Bard created fictitious citations. Cohen's lawyer then plopped the whole thing wholesale into a document for a judge. Judge reads the document and asks Cohen's lawyer to provide copies of the citations (which aren't real). Only the best!
I went to a panel seminar on AI in the legal arena a few months ago. The presenters had given their talk many times in the past year and said they had to update their slideshow daily as new stuff came in because so much is happening. I bet this snafu just made it into their PowerPoint.