The trailer features footage from the original Japanese film, called Kairo. One shot in particular features a plane crashing. The shot was re-done for the final film
The cable that Josh takes into the other room with him is a Parallel Cable but the one used in the hanging is a UTP Network Cable. Furthermore, Mattie refers to the cable as "My boyfriend hung himself with a phone cable."
When the Help Me messages appear on the screen during the group online chat session the appearance of the text goes from "Help Me" to "HelpMe" between shots.