What should I do with AI-suggested references I cannot find?

My co-presenter admired the final slide: “The references make it look properly researched.” I had asked an AI tool for sources for our short talk about poster design. It returned three neatly formatted entries.

I cannot locate two of them. The web address attached to the third opens a publication that does not match the title on the slide. I have not shown the draft to the organiser yet.

My co-presenter says we can leave the references in and look harder after rehearsal. I want to remove the unsupported claims now, but that means shortening the explanation I was pleased with.

How far would you investigate before deciding a reference is unusable? I do not want to call a real publication invented because my search was poor. I also do not want neat formatting to do the work of evidence.