Greg falls off of the cliff where Sam's body is still hanging from her rope from the first movie. He's later found on the bone pit, barely alive. But in the first movie, Sam's body is above a water-filled pit which Juno falls into and finishes off one of The Crawlers. They'd already found the bone pit in a different location.
While Vaines unclasp his holster and takes the gun out, his thumbnail looks completely different from the one holding the camera. The last-mentioned thumbnail lets to assume that the cameraman is a much younger person than Vaines.