The Volvo's wing mirror extenders disappear and reappear as they're arriving at the first caravan site.
When Chris and Tina first arrive at the Abbey he is wearing gaiters. When they are inside the Abbey he's not wearing them but when they go outside again he is wearing them.
Early in the film, when Tina's hair is being brushed by her mother, there is a cut to Tina with her mother visible behind her. Although we can hear her talking, her mouth is shut. Out of sync audio/visuals are a trademark of director Ben Wheatley's editing style (see also: Kill List)
Chris says he favours the Abbey Oxford as a caravan, but his caravan is labelled as an Abbey Cachet. This has led some to consider this as a goof, however Cachet is just a trim level available on Abbey Oxford caravans, like L or GL or GT for cars.