If you click on the article you can see a full list of the hallucinations they found. They did put in the effort to look for plausible partial matches, but most of them are some variation of "No author or title match. Doesn't exist in publication."

Here's a random one I picked as an example.

Paper: https://openreview.net/pdf?id=IiEtQPGVyV

Reference: Asma Issa, George Mohler, and John Johnson. Paraphrase identification using deep contextual- ized representations. In Proceedings of the 2018 Conference on Empirical Methods in Natural Language Processing (EMNLP), pp. 517–526, 2018.

Asma Issa and John Johnson don't appear to exist. George Mohler does, but it doesn't look like he works in this area (https://www.georgemohler.com/). No paper with that title exists. There are some with sort of similar titles (https://arxiv.org/html/2212.06933v2 for example), but none that really make sense as a citation in this context. EMNLP 2018 exists (https://aclanthology.org/D18-1.pdf), but that page range is not a single paper. There are papers in there that contain the phrases "paraphrase identification" and "deep contextualized representations", so you can see how an LLM might have come up with this title.