The Tragedy at Marsdon Manor - S3-E6
Other mistake: Investigating Poirot's investigation, the clumsy constable crushes a tiny egg under his foot. Poirot crawls to him and points with his cane at the other eggs in the bush. But he points practically at his shoe, and the eggs are in a different spot to the left. (00:20:10)
How Does Your Garden Grow? - S3-E2
Other mistake: After Katrina is arrested, Mr. Delafointaine is reading about it on the newspaper. The newspaper is dated Thursday 23rd May 1935. The date is correct, the whole investigation does happen in a day, starting around 10 AM; Poirot is greeted by the couple with "Good afternoon" and to imagine that by the time he gets to their home Katrina's news (complete with picture of the arrest!) is already in a late edition of the newspaper (a local one, at that) is a bit too much of a stretch, with all the steps taken for the investigation, everything in broad daylight. (00:43:20)
