Listen to when Rachel goes through the layers of her trifle. She starts off with normal stuff (jam etc.) then the beef and then bananas. Now if the pages in the cook book were stuck together, she would start off with the trifle (so jam etc. on the bottom) then put the beef on top. But she wouldn't put any bananas and cream on top of that because the beef pie recipe wouldn't tell her to put cream on top. It's only a minor thing but it's still a slip up.