Without search, of course. In theory this should be easy, because clearly the Wikipedia data it's in the model.
In my mostly unscientific RAG experiments I found that larger models were more likely to hallucinate in a RAG setting. I think that it's because they have more world knowledge. As an example, when asking about safety legislation in Ireland, Claude got hooked on the notion that OSHA was involved, which clearly is not true, while the smaller models just said that they couldn't find any information (which was the correct answer).