Echo what Aerbabe said - your instructor should do pfl's over small fields - examiner will do it over a airfield and you will have to land it.
My pfl on the gft was at Goodwood (having trained at Easteigh) 2500ft o/h - examiner 'failed' the engine and i was told to land it.
Another trick to watch for, depending on aircraft being used - I flew AA5's and the fuses/cb's were on the right lower section of the panel - various instructors & examiner used to pull the odd fuse to see if you noticed anything wrong when scanning. ie t & p's not indicating or a warning light coming on.