Other mistake: On the first morning at Manderlay, as the girl is leaving the dining room, she slips and nearly falls but Frith is there to catch her, but Frith was way into the dining room; there is no way he could have been close enough to catch her.
Other mistake: When Maxim and the girl are in the beach cottage after a ship has run aground, Maxim sits in a black chair right next to a lamp that is covered in cobwebs - the place has been empty for more than a year; no-one has cleaned it or been in it, except for Ben, the weird one - but when Maxim sat in the chair, there was no dust rising up and there's not a cobweb to be seen.
Chosen answer: From the screenplay of "Rebecca" which I found on-line, and verified by looking at two different versions, the entirety of the line is: "By the way, what do you do with old bones? Bury them, eh what? However, for the time being - you know, Max, I'm getting awfully fed up with my job as a motor-car salesman."
Michael Albert