This is the first and, as of October 21, 2014, only episode of Forever to be rated TV-14 instead of the normal TV-PG.
"J. Ellroy" in the library check-out ledger is a nod to James Ellroy, author of "The Black Dahlia," a fictional account of the 1947 Los Angeles unsolved murder case.
When Henry is at the crime scene of the present day Mary Kelly the screen of the cell phone is showing the dial screen during the conversation.