Factual error: The whole Egyptian mythos and references are incredibly sketchy: at first it is said that Foyle was born "on the 21st day of Proyet." Leaving aside the fact that Proyet is a season rather than a month and that it simply would not translate automatically into a matching month and day of the Gregorian calendar, it still wouldn't be the 21st of December as stated because Proyet fell rather in a January to May range. Not just that, but in the second half of the episode it's simply identified as "Midsummer", when Proyet was part of Winter and obviously seasons in Australia are the polar opposites of seasons in Egypt.
Factual error: Ignoring the fact that there was no such Pharaoh as "Memses", in the cabinet inventory the missing item is listed as follows: "'Silver stirrup ring, in the reign of King Memses, Dynasty Five, 2600 BC." If it were 2600 BC, it would be Dynasty Three maybe, but not Five, which started just past 2500.
Factual error: Miss Fisher and the crew on 21 December 1928 dance to the glorious rendition of "I'm Sailing On A Sunbeam" by Des Tooley featuring Frank Coughlan, playing a record that was released only in 1930.
Answer: Louisa's watch was broken during the struggle to get away from her attacker.
Bishop73