Factual error: Behind Jack and Miss Fisher as they are waiting to get an answer about the whereabouts of Jane's mother there's a wall calendar that has November 4 as a Tuesday - wrong for 1928, and also inconsistent with the other calendar seen in the episode, in the kitchen. (00:43:00)
Continuity mistake: When Derek's uncle arrives during his interrogation, the badge and pen in front of Jack change position entirely. When the original camera angle is used again, the objects are exactly where they first appeared. (00:28:05 - 00:29:20)
Factual error: The calendar behind Hugh when Dot restores the beer coaster points at November, consistent with the pacing of the show. It's not a November 1928 calendar, though, the first day should have been a Thursday. (00:24:00)
Other mistake: The clock on the lounge's desk signals the same time for the whole scene's duration (when the girls spot the strange woman waiting outside), which lasts much longer than a minute. (00:08:20 - 00:09:50)
Continuity mistake: As Miss Fisher explains how to eat asparagi, the dark haired girl has her fingers on the veggie in a different position in every shot. (00:02:00)
Continuity mistake: When Jack and Hugh arrive during Miss Fisher's judo lesson with the girls, the two outraged ladies walk out of the room twice. (00:15:55)
Answer: Louisa's watch was broken during the struggle to get away from her attacker.
Bishop73