The episode title, My Brother's Keeper, is taken from the original story of Cain and Abel in the Bible. When asked about the whereabouts of Abel (who Cain has just murdered), Cain replies "I know not. Am I my brother's keeper?"
During the scene where Ella and Maze enter the hotel looking for Ella's brother. Ella is looking at the hotel registration book and she sees the name Michael Knight, but if you look closely at the additional names in the book they belong to actual crew members of the show.
The title is spoken by Amenadiel.