I haven't played with commentary yet, so I don't know if this is mentioned or widely known, but I enjoyed seeing that Emil Haskins' apartment in The Blackwell Epiphany is the same as Jack and Rajshree Lauders' in The Shivah, another game from Wadjet Eye that takes place in the Blackwell universe. At first I thought that they could be different apartments in the same building, but then Emil confirmed it was the same one when he said that he was renting it from an Indian lady (that would be Rajshree).

After taking a screenshot from each game, you can even see that they have the same view from their windows.

Have you found any other references?