Yellow tape on earth straps is a requirement as is an indication on the ignition swith as to which way is off. Battery isolation switch should also have an arrow indicating direction to turn off.
Make sure battery terminals are covered with either plastic caps or tape, as I have been pulled up before for this.
Each time you are scrutineered you come across a different item that the scrutineer will comment upon, some will over look some things that another would pick up on! Don't get stressed about it, but just make sure you have a roll of tank tape with you and a variety of coloured pvc tape! You can fix anything then!!
Aves is right about driving on the road with race numbers, if you must, cover with a taped 'X', as suggested. Otherwise apply at the circuit. Gives a bad impression...people think that you are road-racing, which, as we all know, is illegal.
Good luck
Andrew