The comment about the year being 1929 is incorrect. In the book the events of Strong Poison happened between December 1929 and January 1930, dealing with a death that happened in June 1929. Have His Carcase, whilst not specifying the year, started on Thursday 18th June. The dates were changed in the TV series so that the weather in which they were filming was suitable for the dates specified. Lord Peter tells us in the 'quarrel' scene that they had known each other eighteen months at this point, meaning that this must be the June in the year following the second trial in Strong Poison. When they changed the dates for the TV series, they correctly changed the date to the 16th October 1930 but rather inexplicably changed the day from Thursday to Wednesday, making the day of the week incorrect for the date of the year. They also overlooked changing the period of time Lord Peter mentions in the quarrel. In the book, they met in December 1929 and have the quarrel in June 1931, a period of eighteen months almost exactly. For the series they moved the events so that they met in June 1929 and have the quarrel in October 1930, a period of only sixteen months.
Extremely faithful adaption of novel.
It is stated that Harriet Vane discovers the body on Wednesday, 16th October. Specifying the day of the week means that the action must take place in either 1929 or possibly 1935. However since action in Strong Poison takes place in May to July 1929 (based on a murder that took place in February 1929) and action here follows that within a short time, it must be October 1929.