(at around 25 mins) When Specs and Tucker analyze the footage of young Josh, the "Panasonic" VCR logo has been worn away in places so that it reads "Panic" instead.
The hospital featured in the film (Linda Vista Community Hospital) has featured in over thirty movies--mainly horror films--many TV series and also music videos.
Lindsay Seim portrays a younger version of Elise Rainier, Lin Shaye's character in the Insidious films. Because Lin has such a distinct voice, she was dubbed over Lindsay's. You don't hear Lindsay 's voice at all in the movie.
(at around 22 mins) When Specs and Tucker enter Elise's house, there is an African Tribal painting hanging on the wall. It is the same painting seen hanging in Daniel's study in Activité paranormale 2 (2010) and in the Grandmother's house in Activité paranormale 3 (2011).
There is an Australian flag in the corner of Dalton's room in the Lambert house. Leigh Whannell (Specs, writer of Insidieux (2010)), Rose Byrne, Angus Sampson and James Wan (writer and director of this second film) all come from Australia; however, Wan was born in Malaysia, but later moved to Australia.