It is mentioned that Karl Arnold and his wife had been divorced for 5 years. However in Arnold's "family photo", there is no age difference between the photos of the kids and them in the present.
After Gideon is done impersonating the victim screaming for help, Morgan says, "What are you doing?" but his lips don't move.
Fay told Hotchner that Karl had just called an hour ago. After Hotchner hangs up with Fay, any other time, he would have contacted Garcia to look at phone records and could have identified the number that had called Fay and possibly the location.