James May eating with a napkin covering his head is a reference to a French dish made of a small songbird called the ortolan. It is captured alive, force-fed, then drowned in Armagnac, roasted whole and eaten that way, bones and all. While consuming this dish, diners traditionally draped their heads with linen napkins to preserve the precious aromas and, some believe, to hide from God.
Jeremy Clarkson saying that it's hard to find Citroen CX Safaris "as most have been turned into motorhomes" is a reference to Building Motor Homes (2010)], in which he converted a CX Safari into a multi-storey motorhome that he described as his "Citroen Grand Design". Hammond, on the other hand, described it as "a block of flats on top of an old Citroen".
The first time FPV drone footage is shot and used in The Grand Tour.
Jeremy Clarkson referring to jumping from a moving vehicle as "do(ing) a George Michael" stems from a 2013 incident where the famed singer fell out of a moving vehicle on the M1 motorway in Hertfordshire, UK. George sustained minor injuries.