I often think about all the camera crew people, "jungle" team etc, the people around Ant & Dec as they enter the camp - a really overcrowded scene, most of whom are supposed to be out of shot and who the "celebrities" have to pretend aren't there.
Whenever there's a "filmed in the dark" segment, screech and someone leaps out of bed going "Ooooh there's a rat in the camp", I think of someone marching in 30 secs earlier with a rat in a box before clearing off so the filming can start.